Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2019	May 01, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	Sientra, Inc.
Entity Central Index Key	0001551693
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		29,215,704
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Trading Symbol	SIEN

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 61,955	$ 86,899
Accounts receivable, net of allowances of $2,684 and $2,428 at March 31, 2019 and December 31, 2018, respectively	24,767	22,527
Inventories, net	27,242	24,085
Prepaid expenses and other current assets	3,411	2,612
Total current assets	117,375	136,123
Property and equipment, net	3,146	2,536
Goodwill	12,507	12,507
Other intangible assets, net	15,915	16,495
Other assets	22,682	698
Total assets	171,625	168,359
Current liabilities:
Current portion of long-term debt	12,998	6,866
Accounts payable	15,109	13,184
Accrued and other current liabilities	30,416	27,697
Legal settlement payable		410
Customer deposits	10,892	9,936
Sales return liability	8,016	6,048
Total current liabilities	77,431	64,141
Long-term debt	24,416	27,883
Deferred and contingent consideration	6,531	6,481
Warranty reserve and other long-term liabilities	21,017	2,976
Total liabilities	129,395	101,481
Commitments and contingencies (Note 14)
Stockholders’ equity:
Preferred stock, $0.01 par value – Authorized 10,000,000 shares; none issued or outstanding
Common stock, $0.01 par value — Authorized 200,000,000 shares; issued 29,274,377 and 28,701,494 and outstanding 29,201,650 and 28,628,767 shares at March 31, 2019 and December 31, 2018 respectively	292	286
Additional paid-in capital	430,779	428,949
Treasury stock, at cost (72,727 shares at March 31, 2019 and December 31, 2018)	(260)	(260)
Accumulated deficit	(388,581)	(362,097)
Total stockholders’ equity	42,230	66,878
Total liabilities and stockholders’ equity	$ 171,625	$ 168,359

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Accounts receivable, allowances (in dollars)	$ 2,684	$ 2,428
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	29,274,377	28,701,494
Common stock, shares outstanding	29,201,650	28,628,767
Treasury stock, shares	72,727	72,727

Condensed Consolidated Statements of Operations - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Net sales	$ 17,552,000	$ 14,676,000
Cost of goods sold	6,474,000	6,097,000
Gross profit	11,078,000	8,579,000
Operating expenses:
Sales and marketing	20,401,000	15,256,000
Research and development	3,054,000	2,751,000
General and administrative	13,474,000	9,499,000
Total operating expenses	36,929,000	27,506,000
Loss from operations	(25,851,000)	(18,927,000)
Other income (expense), net:
Interest income	304,000	40,000
Interest expense	(952,000)	(655,000)
Other income (expense), net	15,000	119,000
Total other income (expense), net	(633,000)	(496,000)
Loss before income taxes	(26,484,000)	(19,423,000)
Income tax (benefit) expense	0	0
Net loss	$ (26,484,000)	$ (19,423,000)
Basic and diluted net loss per share attributable to common stockholders	$ (0.91)	$ (0.99)
Weighted average outstanding common shares used for net loss per share attributable to common stockholders:
Basic and diluted	29,099,382	19,613,417

Condensed Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	Common stock	Treasury stock	Additional paid-in capital	Accumulated deficit
Balance, beginning of year at Dec. 31, 2017	$ 27,623	$ 194	$ (260)	$ 307,159	$ (279,470)
Balance, beginning of year (in shares) at Dec. 31, 2017		19,474,702	72,727
Stock-based compensation	2,548			2,548
Employee stock purchase program (ESPP)	391	$ 1		390
Employee stock purchase program (ESPP) (in shares)		62,491
Vested restricted stock		$ 3		(3)
Vested restricted stock (in shares)		271,936
Shares withheld for tax obligations on vested RSUs	(1,296)	$ (1)		(1,295)
Shares withheld for tax obligations on vested RSUs, shares		(92,760)
Net loss	(19,423)				(19,423)
Balance, end of year at Mar. 31, 2018	9,843	$ 197	$ (260)	308,799	(298,893)
Balance, end of year (in shares) at Mar. 31, 2018		19,716,369	72,727
Balance, beginning of year at Dec. 31, 2018	66,878	$ 286	$ (260)	428,949	(362,097)
Balance, beginning of year (in shares) at Dec. 31, 2018		28,701,494	72,727
Stock-based compensation	3,772			3,772
Stock option exercises	106			106
Stock option exercises (in shares)		45,453
Employee stock purchase program (ESPP)	683	$ 1		682
Employee stock purchase program (ESPP) (in shares)		68,899
Vested restricted stock		$ 7		(7)
Vested restricted stock (in shares)		671,245
Shares withheld for tax obligations on vested RSUs	(2,725)	$ (2)		(2,723)
Shares withheld for tax obligations on vested RSUs, shares		(212,714)
Net loss	(26,484)				(26,484)
Balance, end of year at Mar. 31, 2019	$ 42,230	$ 292	$ (260)	$ 430,779	$ (388,581)
Balance, end of year (in shares) at Mar. 31, 2019		29,274,377	72,727

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net loss	$ (26,484)	$ (19,423)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	831	880
Provision for doubtful accounts	342	233
Provision for warranties	273	183
Provision for inventory	289	199
Amortization of acquired inventory step-up		59
Change in fair value of warrants	(87)	(121)
Change in fair value of contingent consideration	185	621
Change in deferred revenue	384	(99)
Amortization of debt discount and issuance costs	56	51
Stock-based compensation expense	3,700	2,548
Payments of contingent consideration liability in excess of acquisition-date fair value	(630)
Changes in assets and liabilities, net of effects from acquisitions:
Accounts receivable	(2,583)	(5,735)
Inventories	(3,373)	(1,191)
Prepaid expenses, other current assets and other assets	396	(1,009)
Insurance recovery receivable		(10)
Accounts payable	1,853	4,684
Accrued and other liabilities	(2,312)	948
Legal settlement payable	(410)
Customer deposits	956	8
Sales return liability	1,968	4,400
Net cash used in operating activities	(24,646)	(12,774)
Cash flows from investing activities:
Purchase of property and equipment	(610)	(142)
Net cash used in investing activities	(610)	(142)
Cash flows from financing activities:
Proceeds from exercise of stock options	106
Proceeds from issuance of common stock under ESPP	683	391
Tax payments related to shares withheld for vested restricted stock units (RSUs)	(2,725)	(1,296)
Gross borrowings under the Revolving Loan	4,183	9,033
Repayment of the Revolving Loan	(1,565)	(5,735)
Payments of contingent consideration up to acquisition-date fair value	(370)
Deferred financing costs		(6)
Net cash provided by financing activities	312	2,387
Net decrease in cash, cash equivalents and restricted cash	(24,944)	(10,529)
Cash, cash equivalents and restricted cash at:
Beginning of period	87,242	26,931
End of period	62,298	16,402
Reconciliation of cash, cash equivalents, and restricted cash to the consolidated balance sheets
Cash and cash equivalents	61,955	16,059
Restricted cash included in other assets	$ 343	$ 343
Restricted Cash Noncurrent Asset Statement Of Financial Position Extensible List	us-gaap:OtherNoncurrentAssetsMember	us-gaap:OtherNoncurrentAssetsMember
End of period	$ 62,298	$ 16,402
Supplemental disclosure of cash flow information:
Interest paid	903	586
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment in accounts payable and accrued liabilities	$ 273	$ 1,530

Formation and Business of the Company

3 Months Ended

Mar. 31, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Formation and Business of the Company

1.	Formation and Business of the Company

a.

Formation

Sientra, Inc. (“Sientra”, the “Company,” “we,” “our” or “us”), was incorporated in the State of Delaware on August 29, 2003 under the name Juliet Medical, Inc. and subsequently changed its name to Sientra, Inc. in April 2007. The Company acquired substantially all the assets of Silimed, Inc. on April 4, 2007. The purpose of the acquisition was to acquire the rights to the silicone breast implant clinical trials, related product specifications and pre-market approval, or PMA, assets. Following this acquisition, the Company focused on completing the clinical trials to gain FDA approval to offer its silicone gel breast implants in the United States.

In March 2012, the Company announced it had received approval from the FDA for its portfolio of silicone gel breast implants, and in the second quarter of 2012 the Company began commercialization efforts to sell its products in the United States. The Company, based in Santa Barbara, California, is a medical aesthetics company that focuses on serving board-certified plastic surgeons and offers a portfolio of silicone shaped and round breast implants, scar management, tissue expanders, and body contouring products.

In November 2014, the Company completed an initial public offering, or IPO, and its common stock is listed on the Nasdaq Stock Exchange under the symbol “SIEN.”

b.

Regulatory Review of Vesta Manufacturing

The Company has engaged Vesta Intermediate Funding, Inc., or Vesta, a Lubrizol Lifesciences company, for the manufacture and supply of the Company’s breast implants. On March 14, 2017, the Company announced it had submitted a site-change pre-market approval, or PMA, supplement to the FDA for the manufacture of the Company’s PMA-approved breast implants at the Vesta manufacturing facility. On January 30, 2018, the Company announced the FDA has granted approval of the site-change supplement for the Company’s contract manufacturer, Vesta, to manufacture its silicone gel breast implants. In support of the move to the Vesta manufacturing facility, the Company also implemented new manufacturing process improvements which, in consultation with the FDA, required three (3) additional PMA submissions. In addition to approving the manufacturing site-change PMA supplement, the FDA approved the Company’s three (3) process enhancement submissions on January 10, 2018, January 19, 2018 and April 17, 2018.

c.

Follow-On Offering

On May 7, 2018, the Company completed an underwritten follow-on public offering of 7,407,408 shares of its common stock at $13.50 per share, as well as 1,111,111 additional shares of its common stock pursuant to the full exercise of the over-allotment option granted to the underwriters. Net proceeds to the Company were approximately $107.6 million after deducting underwriting discounts and commissions of $6.9 million and offering expenses of approximately $0.5 million.

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2.	Summary of Significant Accounting Policies

a.

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements in this Quarterly Report on Form 10-Q have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, and the rules and regulations of the U.S. Securities and Exchange Commission, or SEC. Accordingly, they do not include certain footnotes and financial presentations normally required under accounting principles generally accepted in the United States of America for complete financial reporting. The interim financial information is unaudited, but reflects all normal adjustments and accruals which are, in the opinion of management, considered necessary to provide a fair presentation for the interim periods presented. The accompanying condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 filed with the SEC on March 14, 2019, or the Annual Report. The results for the three months ended March 31, 2019 are not necessarily indicative of results to be expected for the year ending December 31, 2019, any other interim periods, or any future year or period.

b.

Liquidity

Since the Company’s inception, it has incurred significant net operating losses and the Company anticipates that losses will continue in the near term. The Company expects its operating expenses will continue to grow as they expand operations. The Company will need to generate significant net sales to achieve profitability. To date, the Company has funded operations primarily with proceeds from the sales of preferred stock, borrowings under term loans, sales of products since 2012, and the proceeds from the sale of common stock in public offerings.

The accompanying condensed consolidated financial statements have been prepared on a going concern basis, which implies the Company will continue to realize its assets and discharge its liabilities in the normal course of business. As of March 31, 2019, the Company had cash and cash equivalents of $62.0 million. Since inception, the Company has incurred recurring losses from operations and cash outflows from operating activities. The continuation of the Company as a going concern is dependent upon many factors including liquidity and the ability to raise capital. The Company received FDA approval of their PMA supplement on April 17, 2018 and was then able to access a $10.0 million term loan pursuant to an amendment to the credit agreement with MidCap Financial Trust, or MidCap. In addition, in February 2018, the Company entered into an At-The-Market Equity Offering Sales Agreement with Stifel, Nicolaus & Company, Incorporated, or Stifel, as sales agent pursuant to which the Company may sell, from time to time, through Stifel, shares of our common stock having an aggregate gross offering price of up to $50.0 million. As of March 31, 2019, the Company has not sold any common stock pursuant to the sales agreement. Further, on May 7, 2018, the Company completed a public offering of its common stock, raising approximately $107.6 million in net proceeds after deducting underwriting discounts and commissions and other offering expenses.

The Company believes that its cash and cash equivalents will be sufficient to fund its operations for at least the next 12 months. To fund ongoing operating and capital needs, the Company may need to raise additional capital in the future through the sale of equity securities and incremental debt financing.

c.

Use of Estimates

The preparation of the condensed consolidated financial statements, in conformity with GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates.

d.

Significant Accounting Policies

Revenue Recognition

The Company recognizes revenue when the Company transfers control of promised goods or services to customers in an amount that reflects the consideration to which the Company expects to be entitled to in exchange for those goods or services. See Note 3 - Revenue for further discussion.

There have been no other changes to the accounting policies during the three months ended March 31, 2019, as compared to the significant accounting policies described in the “Notes to Financial Statements” in the Annual Report other than the adoption of Topic 842, as discussed in “Recent Accounting Pronouncements” and Note 9.

e.

Recent Accounting Pronouncements

Recently Adopted Accounting Standards

In February 2016, the FASB issued Accounting Standards Update, or ASU, 2016-02, Leases (Topic 842). This ASU requires a company to recognize lease assets and liabilities arising from operating leases in the statement of financial position. This ASU does not significantly change the previous lease guidance for how a lessee should recognize the recognition, measurement, and presentation of expenses and cash flows arising from a lease. Additionally, the criteria for classifying a finance lease versus an operating lease are substantially the same as the previous guidance. This ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and early adoption was permitted. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842) Targeted Improvements, amending certain aspects of the new leasing standard. The amendment allowed an additional optional transition method whereby an entity records a cumulative effect adjustment to opening retained earnings in the year of adoption without restating prior periods. The Company adopted Topic 842 on January 1, 2019 electing the package of practical expedients permitted under the transition guidance, which allowed the Company to carry forward the historical lease classification, the assessment on whether a contract is or contains a lease, and the initial direct costs for any leases that exist prior to adoption of the new standard. The Company has not restated prior periods under the optional transition method. The adoption of ASU 2016-02 on January 1, 2019 resulted in the recognition of right-of-use assets of approximately $22.7 million, lease liabilities of approximately $22.9 million and no cumulative-effect adjustment on retained earnings on its Condensed Consolidated Balance Sheets. Refer to Note 9 - Leases for further details.

In February 2018, the FASB issued ASU 2018-02, Income Taxes (Topic 740), which allows for an entity to elect to reclassify the income tax effects on items within accumulated other comprehensive income resulting from U.S. Tax Cuts and Jobs Act to retained earnings. The guidance is effective for fiscal years beginning after December 15, 2018 with early adoption permitted, including interim periods within those years. The Company adopted ASC 2018-02 and elected to not reclassify the income tax effects under ASU 2018-02, as it does not have a material impact on the condensed consolidated financial statements.

f.

Reclassifications

Certain reclassifications have been made to prior year amounts to conform to the current year presentation.

Revenue

3 Months Ended

Mar. 31, 2019

Revenue From Contract With Customer [Abstract]

Revenue

3.

Revenue

Revenue Recognition

The Company generates revenue primarily through the sale and delivery of promised goods or services to customers and recognizes revenue when control is transferred to customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for the goods or services. Performance obligations typically include the delivery of promised products, such as breast implants, tissue expanders, BIOCORNEUM, miraDry Systems and bioTips, along with service-type warranties and deliverables under certain marketing programs. Other deliverables are sometimes promised, but are ancillary and insignificant in the context of the contract as a whole. Sales prices are documented in the executed sales contract, purchase order or order acknowledgement prior to the transfer of control to the customer. Customers may enter into a separate extended service agreement to purchase an extended warranty for miraDry products from the Company whereby the payment is due at the inception of the agreement. Typical payment terms are 30 days for Breast Products and direct sales of consumable miraDry products, and tend to be longer for capital sales of miraDry Systems and sales to miraDry distributors, but do not extend beyond one year. For delivery of promised products, control transfers and revenue is recognized upon shipment, unless the contractual arrangement requires transfer of control when products reach their destination, for which revenue is recognized once the product arrives at its destination. Revenue for extended service agreements are recognized ratably over the term of the agreements.

For Breast Products, with the exception of the Company’s BIOCORNEUM scar management products, the Company allows for the return of products from customers within six months after the original sale, which is accounted for as variable consideration. Reserves are established for anticipated sales returns based on the expected amount calculated with historical experience, recent gross sales and any notification of pending returns. The estimated sales return is recorded as a reduction of revenue and as a sales return liability in the same period revenue is recognized. Actual sales returns in any future period are inherently uncertain and thus may differ from the estimates. If actual sales returns differ significantly from the estimates, an adjustment to revenue in the current or subsequent period would be recorded. The Company has established an allowance for sales returns of $8.0 million and $6.0 million as of March 31, 2019 and December 31, 2018 respectively, recorded as “sales return liability” on the condensed consolidated balance sheets.

The following table provides a rollforward of the sales return liability (in thousands):

	Sales return liability
Balance as of December 31, 2018	$	6,048
Addition to reserve for sales activity		22,617
Actual returns		(21,040	)
Change in estimate of sales returns		391
Balance as of March 31, 2019	$	8,016

For Breast Products, a portion of the Company’s revenue is generated from the sale of consigned inventory of breast implants maintained at doctor, hospital, and clinic locations. For these products, revenue is recognized at the time the Company is notified by the customer that the product has been implanted, not when the consigned products are delivered to the customer’s location.

For miraDry, in addition to domestic and international direct sales, the Company leverages a distributor network for selling the miraDry System internationally. The Company recognizes revenue when control of the goods or services is transferred to the distributors. Standard terms in both direct sales agreements (domestic and international), and international distributor agreements do not allow for trial periods, right of return, refunds, payment contingent on obtaining financing or other terms that could impact the customer’s payment obligation.

Arrangements with Multiple Performance Obligations

The Company has determined that the delivery of each unit of product in the Company’s revenue contracts with customers is a separate performance obligation. The Company’s revenue contracts may include multiple products or services, each of which is considered a separate performance obligation. For such arrangements, the Company allocates revenue to each performance obligation based on its relative standalone selling price. The Company generally determines standalone selling prices based on observable prices or using an expected cost plus margin approach when an observable price is not available. The Company invoices customers once products are shipped or delivered to customers depending on the negotiated shipping terms.

The Company introduced its Platinum20 Limited Warranty Program, or Platinum20, in May 2018 on all OPUS breast implants implanted in the United States or Puerto Rico on or after May 1, 2018. Platinum20 provides for financial assistance for revision surgeries and no-charge contralateral replacement implants upon the occurrence of certain qualifying events. The Company considers Platinum20 to have an assurance warranty component and a service warranty component. The assurance component is recorded as a warranty liability at the time of sale (as discussed in Note 6). The Company considers the service warranty component as an additional performance obligation and defers revenue at the time of sale based on the relative estimated selling price, by estimating a standalone selling price using the expected cost plus margin approach for the performance obligation. Inputs into the expected cost plus margin approach include historical incidence rates, estimated replacement costs, estimated financial assistance payouts and an estimated margin. The liability for unsatisfied performance obligations under the service warranty as of March 31, 2019 and December 31, 2018 was $0.6 million and $0.4 million respectively. The short-term obligation related to the service warranty as of both March 31, 2019 and December 31, 2018 was $0.2 million and is included in “accrued and other current liabilities” on the condensed consolidated balance sheets. The long-term obligation related to the service warranty as of both March 31, 2019 and December 31, 2018 was $0.3 million, and is included in “warranty reserve and other long-term liabilities” on the condensed consolidated balance sheets. The performance obligation is satisfied at the time that Platinum20 benefits are provided and are expected to be satisfied over the following 6 to 24 month period for financial assistance and 20 years for product replacement. Revenue recognized for the service warranty performance obligations for the three months ended March 31, 2019 was immaterial.

Practical Expedients and Policy Election

The Company generally expenses sales commissions when incurred because the amortization period would have been one year or less. These costs are recorded within sales and marketing expenses.

The Company does not adjust accounts receivable for the effects of any significant financing components as customer payment terms are shorter than one year.

The Company has elected to account for shipping and handling activities performed after a customer obtains control of the products as activities to fulfill the promise to transfer the products to the customer. Shipping and handling activities are largely provided to customers free of charge for the Breast Products segment. The associated costs were $0.4 million and $0.2 million for the three months ended March 31, 2019 and 2018 respectively. These costs are viewed as part of the Company’s sales and marketing programs and are recorded as a component of sales and marketing expense in the condensed consolidated statement of operations as an accounting policy election. For the miraDry segment, shipping and handling charges are typically billed to customers and recorded as revenue. The shipping and handling costs incurred are recorded as a component of cost of goods sold in the condensed consolidated statement of operations. The associated costs were $0.1 million for both the three months ended March 31, 2019 and 2018.

Fair Value of Financial Instruments

3 Months Ended

Mar. 31, 2019

Financial Instruments Owned At Fair Value [Abstract]

Fair Value of Financial Instruments

4.	Fair Value of Financial Instruments

The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable, accrued liabilities, customer deposits and sales return liability are reasonable estimates of their fair value because of the short maturity of these items. The fair value of the common stock warrant liability and contingent consideration are discussed in Note 5. The fair value of the debt is based on the amount of future cash flows associated with the instrument discounted using the Company’s estimated market rate. As of March 31, 2019, the carrying value of the long-term debt was not materially different from the fair value.

Fair Value Measurements

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

5.	Fair Value Measurements

Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs.

Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable:

•

Level 1 — Quoted prices in active markets for identical assets or liabilities.

•

Level 2 — Observable inputs (other than Level 1 quoted prices) such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data.

•

Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.

The Company’s common stock warrant liabilities are carried at fair value determined according to the fair value hierarchy described above. The Company has utilized an option pricing valuation model to determine the fair value of its outstanding common stock warrant liabilities. The inputs to the model include fair value of the common stock related to the warrant, exercise price of the warrant, expected term, expected volatility, risk-free interest rate and dividend yield. The warrants are valued using the fair value of common stock as of the measurement date. The Company historically has been a private company and lacks company-specific historical and implied volatility information of its stock. Therefore, it estimates its expected stock volatility based on the historical volatility of publicly traded peer companies for a term equal to the remaining contractual term of the warrants. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve for time periods approximately equal to the remaining contractual term of the warrants. The Company has estimated a 0% dividend yield based on the expected dividend yield and the fact that the Company has never paid or declared dividends. As several significant inputs are not observable, the overall fair value measurement of the warrants is classified as Level 3.

The Company assessed the fair value of the contingent consideration for future royalty payments related to the acquisition of BIOCORNEUM and the contingent consideration for the future milestone payments related to the acquisition of miraDry using a Monte-Carlo simulation model. Significant assumptions used in the measurement include future net sales for a defined term and the risk-adjusted discount rate associated with the business. As the inputs are not observable, the overall fair value measurement of the contingent consideration is classified as Level 3.

The following tables present information about the Company’s liabilities that are measured at fair value on a recurring basis as of March 31, 2019 and December 31, 2018 and indicate the level of the fair value hierarchy utilized to determine such fair value (in thousands):

	Fair Value Measurements as of
	March 31, 2019 Using:
	Level 1		Level 2		Level 3		Total
Liabilities:
Liability for common stock warrants	$	—		—		26		26
Liability for contingent consideration		—		—		13,032		13,032
	$	—		—		13,058		13,058

	Fair Value Measurements as of
	December 31, 2018 Using:
	Level 1		Level 2		Level 3		Total
Liabilities:
Liability for common stock warrants	$	—		—		113		113
Liability for contingent consideration		—		—		13,847		13,847
	$	—		—		13,960		13,960

The liability for common stock warrants and the current portion of contingent consideration is included in “accrued and other current liabilities” and the long-term liabilities for the contingent consideration are included in “deferred and contingent consideration” in the condensed consolidated balance sheet. The following table provides a rollforward of the aggregate fair values of the Company’s common stock warrants and contingent consideration for which fair value is determined by Level 3 inputs (in thousands):

Warrant Liability
Balance, December 31, 2018	$	113
Change in fair value of warrant liability		(87	)
Balance, March 31, 2019	$	26
Contingent Consideration Liability
Balance, December 31, 2018	$	13,847
Payments of contingent consideration		(1,000	)
Change in fair value of contingent consideration		185
Balance, March 31, 2019	$	13,032

The Company recognizes changes in the fair value of the warrants in “other income (expense), net” in the condensed consolidated statement of operations and changes in contingent consideration are recognized in “general and administrative” expense in the condensed consolidated statement of operations.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Product Warranties

3 Months Ended

Mar. 31, 2019

Product Warranties Disclosures [Abstract]

Product Warranties

6.	Product Warranties

The Company offers a product replacement and limited warranty program for the Company’s silicone gel breast implants, and a product warranty for the Company’s miraDry Systems and consumable bioTips. For silicone gel breast implant surgeries occurring prior to May 1, 2018, the Company provides lifetime replacement implants and up to $3,600 in financial assistance for revision surgeries, for covered rupture events that occur within ten years of the surgery date. The Company introduced its Platinum20 Limited Warranty Program in May 2018, covering OPUS silicone gel breast implants implanted in the United States or Puerto Rico on or after May 1, 2018. The Company considers the program to have an assurance warranty component and a service warranty component. The service warranty component is discussed in Note 3 above. The assurance component is related to the lifetime no-charge contralateral replacement implants and up to $5,000 in financial assistance for revision surgeries, for covered rupture events that occur within twenty years of the surgery date. Under the miraDry warranty, the Company provides a standard product warranty for the miraDry System and bioTips, which the Company considers an assurance-type warranty.

The following table provides a rollforward of the accrued warranties (in thousands):

	Three Months Ended March 31,
	2019			2018
Beginning balance as of January 1	$	1,395		$	1,642
Warranty costs incurred during the period		(139	)		(104	)
Changes in accrual related to warranties issued during the period		244			50
Changes in accrual related to pre-existing warranties		29			133
Balance as of March 31	$	1,529		$	1,721

Net Loss Per Share

3 Months Ended

Mar. 31, 2019

Earnings Per Share [Abstract]

Net Loss Per Share

7.	Net Loss Per Share

Basic net loss per share attributable to common stockholders is computed by dividing net loss by the weighted average number of common shares outstanding during each period. Diluted net loss per common share is computed by dividing net loss available to common stockholders by the weighted average number of common shares and dilutive potential common share equivalents then outstanding, to the extent they are dilutive. Potential common shares consist of shares issuable upon the exercise of stock options and warrants (using the treasury stock method). Dilutive net loss per share is the same as basic net loss per share for all periods presented because the effects of potentially dilutive items were anti-dilutive.

	Three Months Ended March 31,
	2019			2018
Net loss (in thousands)	$	(26,484	)	$	(19,423	)
Weighted average common shares outstanding, basic and diluted		29,099,382			19,613,417
Net loss per share attributable to common stockholders	$	(0.91	)	$	(0.99	)

The Company excluded the following potentially dilutive securities, outstanding as of March 31, 2019 and 2018, from the computation of diluted net loss per share attributable to common stockholders for the three months ended March 31, 2019 and 2018 because they had an anti-dilutive impact due to the net loss attributable to common stockholders incurred for the periods.

	March 31,
	2019		2018
Stock options to purchase common stock		1,469,792		1,600,826
Warrants for the purchase of common stock		47,710		47,710
		1,517,502		1,648,536

Balance Sheet Components

3 Months Ended

Mar. 31, 2019

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

8.	Balance Sheet Components

a.

Allowance for Doubtful Accounts

The Company has established an allowance for doubtful accounts of $2.7 million and $2.4 million as of March 31, 2019 and December 31, 2018, respectively, recorded net against accounts receivable in the balance sheet.

b.

Inventories

Inventories, net consist of the following (in thousands):

	March 31,		December 31,
	2019		2018
Raw materials	$	2,680	$	2,147
Work in progress		2,690		2,110
Finished goods		19,850		18,335
Finished goods - right of return		2,022		1,493
	$	27,242	$	24,085

c.

Property and Equipment

Property and equipment, net consist of the following (in thousands):

	March 31,			December 31,
	2019			2018
Leasehold improvements	$	402		$	402
Manufacturing equipment and toolings		2,463			1,928
Computer equipment		748			682
Software		1,213			1,039
Office equipment		117			156
Furniture and fixtures		934			826
		5,877			5,033
Less accumulated depreciation		(2,731	)		(2,497	)
	$	3,146		$	2,536

Depreciation expense for both the three months ended March 31, 2019 and 2018 was $0.3 million.

Under the terms of the manufacturing agreement with Vesta, upon the commencement of Contract Year One (as defined in the agreement) which occurred following FDA-approval of all submissions related to the site-change PMA supplement for the Vesta manufacturing facility, Vesta was obligated to purchase the manufacturing equipment and tooling that Sientra had originally purchased for the manufacture of Sientra’s breast implant inventory at Vesta’s manufacturing facility. Vesta repurchased the equipment with a net book value of $2.7 million in the third quarter of 2018 through a reduction in the Company’s accounts payable balance owed to Vesta.

d.

Goodwill and Other Intangible Assets, net

The Company has determined that it has two reporting units, Breast Products and miraDry, and evaluates goodwill for impairment at least annually on October 1^st and whenever circumstances suggest that goodwill may be impaired.

The changes in the carrying amount of goodwill during the three months ended March 31, 2019 were as follows (in thousands):

	Breast Products			miraDry		Total
Balances as of December 31, 2018
Goodwill	$	19,156		$	7,629	$	26,785
Accumulated impairment losses		(14,278	)		—		(14,278	)
Goodwill, net	$	4,878		$	7,629	$	12,507

Balances as of March 31, 2019
Goodwill	$	19,156		$	7,629	$	26,785
Accumulated impairment losses		(14,278	)		—		(14,278	)
Goodwill, net	$	4,878		$	7,629	$	12,507

As of March 31, 2019 and December 31, 2018 the miraDry reporting unit had a negative carrying value.

The components of the Company’s other intangible assets consist of the following (in thousands):

	Average
	Amortization		March 31, 2019
	Period		Gross Carrying		Accumulated			Intangible
	(in years)		Amount		Amortization			Assets, net
Intangibles with definite lives
Customer relationships		11	$	11,240	$	(3,878	)	$	7,362
Trade names - finite life		14		5,800		(638	)		5,162
Developed technology		15		3,000		(407	)		2,593
Distributor relationships		9		500		(152	)		348
Non-compete agreement		2		80		(80	)		—
Regulatory approvals		1		670		(670	)		—
Acquired FDA non-gel product approval		11		1,713		(1,713	)		—
Total definite-lived intangible assets			$	23,003	$	(7,538	)	$	15,465

Intangibles with indefinite lives
Trade names - indefinite life	—			450		—			450
Total indefinite-lived intangible assets			$	450	$	—		$	450

	Average
	Amortization		December 31, 2018
	Period		Gross Carrying		Accumulated			Intangible
	(in years)		Amount		Amortization			Assets, net
Intangibles with definite lives
Customer relationships		11	$	11,240	$	(3,486	)	$	7,754
Trade names - finite life		14		5,800		(541	)		5,259
Developed technology		15		3,000		(338	)		2,662
Distributor relationships		9		500		(130	)		370
Non-compete agreement		2		80		(80	)		—
Regulatory approvals		1		670		(670	)		—
Acquired FDA non-gel product approval		11		1,713		(1,713	)		—
Total definite-lived intangible assets			$	23,003	$	(6,958	)	$	16,045

Intangibles with indefinite lives
Trade names - indefinite life	—			450		—			450
Total indefinite-lived intangible assets			$	450	$	—		$	450

Amortization expense for both the three months ended March 31, 2019 and 2018 was $0.6 million. The following table summarizes the estimated amortization expense relating to the Company's definite-lived intangible assets as of March 31, 2019 (in thousands):

	Amortization
Period	Expense
Remainder of 2019	$	1,741
2020		2,209
2021		1,996
2022		1,762
2023		1,545
Thereafter		6,212
	$	15,465

e.

Accrued and Other Current Liabilities

Accrued and other current liabilities consist of the following (in thousands):

	March 31,		December 31,
	2019		2018
Payroll and related expenses	$	4,561	$	6,466
Accrued commissions		4,175		5,321
Accrued equipment		427		18
Deferred and contingent consideration, current portion		6,780		7,645
Audit, consulting and legal fees		2,267		703
Accrued sales and marketing expenses		2,157		1,374
Operating lease liabilities		4,707		—
Finance lease liabilities		42		—
Other		5,300		6,170
	$	30,416	$	27,697

Leases

3 Months Ended

Mar. 31, 2019

Leases [Abstract]

Leases

9.

Leases

The Company leases certain office space, warehouses, distribution facilities and office equipment. The Company also has embedded leases of manufacturing facilities and equipment associated with the Company’s manufacturing contracts. The Company determines if an arrangement contains a lease at inception by evaluating whether the arrangement conveys the right to use an identified asset and whether the Company obtains substantially all of the economic benefits from and has the ability to direct the use of the asset.

Operating and finance lease right-of-use, or ROU, assets and lease liabilities are recognized based on the present value of the future lease payments over the lease term at the commencement date. The Company determines its incremental borrowing rate based on the information available at the commencement date in determining the lease liabilities as the Company’s leases generally do not provide an implicit rate. The ROU assets also include any initial direct costs incurred and any lease payments made at or before the lease commencement date, less lease incentives received. Lease terms may include options to extend or terminate when the Company is reasonably certain that the option will be exercised. The Company elected to apply the short-term lease measurement and recognition exemption in which ROU assets and lease liabilities are not recognized for short-term leases. The Company’s lease agreements generally do not contain material residual value guarantees or material restrictive covenants.

The Company’s leases of office space, warehouses and distribution facilities are treated as operating leases and often contain lease and non-lease components. The Company has elected to account for these lease and non-lease components separately. Non-lease components for these assets are primarily comprised of common-area maintenance, utilities, and real estate taxes that are passed on from the lessor in proportion to the space leased by the Company, and are recognized in operating expenses in the period in which the obligation for those payments was incurred. Lease cost for these operating leases is recognized on a straight-line basis over the lease term in operating expenses.

The Company’s embedded leases of manufacturing facilities and equipment are treated as operating leases and often contain lease and non-lease components. The Company has elected to account for these lease and non-lease components as a single lease component. There may be variability in future lease payments as the amount of the non-lease components is based on the costs of manufacturing and is dependent on the amount and types of units produced. The Company reduces the operating lease liability when the inventory is purchased.

The Company’s leases of office equipment are accounted for as finance leases as they meet one or more of the five finance lease classification criteria. Lease cost for these finance leases is comprised of amortization of the ROU asset and interest expense which are recognized in operating expenses and other income (expense), net.

Components of lease expense were as follows:

		Three Months Ended March 31,
Lease Cost	Classification	2019
Operating lease cost	Operating expenses	$	380
Operating lease cost	Inventory		1,248
Total operating lease cost		$	1,628
Finance lease cost
Amortization of right-of-use assets	Operating expenses		9
Interest on lease liabilities	Other income (expense), net		1
Total finance lease cost		$	10
Variable lease cost	Inventory		2,373
Total lease cost		$	4,011

Short-term lease expense for the three months ended March 31, 2019 was not material.

Supplemental cash flow information related to operating and finance leases for the three months ended March 31, 2019 was as follows (in thousands):

	Three Months Ended March 31,
	2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflows from operating leases	$	1,462
Operating cash outflows from finance leases		9
Right-of-use assets obtained in exchange for new lease obligations:
Operating leases	$	23,046
Finance leases		119

Supplemental balance sheet information, as of March 31, 2019, related to operating and finance leases was as follows (in thousands, except lease term and discount rate):

	March 31,
	2019
Reported as:
Other assets
Operating lease right-of-use assets	$	21,885
Finance lease right-of-use assets		111
Total right-of use assets	$	21,996
Accrued and other current liabilities
Operating lease liabilties	$	4,707
Finance lease liabilities		42
Warranty reserve and other long-term liabilities
Operating lease liabilties		17,548
Finance lease liabilities		66
Total lease liabilities	$	22,363
Weighted average remaining lease term (years)
Operating leases		4
Finance leases		3
Weighted average discount rate
Operating leases		8.19	%
Finance leases		4.28	%

As of March 31, 2019, maturities of the Company’s operating and finance lease liabilities are as follows (in thousands):

Period	Operating leases		Finance leases		Total
Remainder of 2019	$	4,795	$	35	$	4,830
2020		6,245		43		6,288
2021		6,242		36		6,278
2022		5,976		—		5,976
2023		2,654		—		2,654
2024 and thereafter		499		—		499
Total lease payments	$	26,411	$	114	$	26,525
Less imputed interest		4,156		6		4,162
Total operating lease liabilities	$	22,255	$	108	$	22,363

As previously reported in our Annual Report on Form 10-K for the year ended December 31, 2018 and under legacy lease accounting (ASC 840), future minimum lease payments under non-cancellable leases as of December 31, 2018 was as follows (in thousands):

Year Ended December 31:
2020	$	1,325
2021		1,134
2022		1,060
2023		947
2024 and thereafter		1,557
	$	6,023

The table above does not include the minimum purchase obligations of approximately $21.6 million over the five years following December 31, 2018 under the Company’s contracts with its manufacturers which upon adoption of ASU 2016-02 on January 1, 2019 were accounted for as operating lease ROU assets and lease liabilities.

Long-Term Debt and Revolving Loan

3 Months Ended

Mar. 31, 2019

Debt Disclosure [Abstract]

Long-Term Debt and Revolving Loan

10.	Long-Term Debt and Revolving Loan

On July 25, 2017, the Company entered into a Credit and Security Agreement, or the Term Loan Credit Agreement, and a Credit and Security Agreement, or the Revolving Credit Agreement with MidCap, and, together with the Term Loan Credit Agreement, the Credit Agreements, which replaced the Company’s then-existing Silicon Valley Bank Loan Agreement, or the SVB Loan Agreement.

Under the terms of the Term Loan Credit Agreement, as of July 25, 2017, MidCap funded $25.0 million to the Company, or the Closing Date Term Loan. MidCap also made available to the Company until March 31, 2018, a $10.0 million term loan, or the March 2018 Term Loan, subject to the satisfaction of certain conditions, including FDA certifications of the manufacturing facility operated by Vesta, and an additional $5.0 million term loan, subject to the satisfaction of certain conditions, including evidence that the Company’s Net Revenue for the past 12 months was greater than or equal to $75.0 million, as defined in the Term Loan Credit Agreement, collectively the Term Loans. On April 18, 2018, the Company amended the Term Loan Credit Agreement pursuant to which the parties agreed to adjust the date by which the Company must obtain FDA approval of its PMA supplement in order to access the March 2018 Term Loan until April 30, 2018. In April 2018, upon FDA approval of the Company’s PMA supplement, MidCap funded the $10.0 million March Term Loan. Under the Revolving Credit Agreement, MidCap made available to the Company a revolving line of credit, or the Revolving Loan. The amount of loans available to be drawn is based on a borrowing base equal to 85% of the net collectible value of eligible accounts receivable plus 40% of eligible finished goods inventory, or the Borrowing Base, provided that availability from eligible finished goods inventory does not exceed 20% of the Borrowing Base. The Company used a portion of the $25.0 million of proceeds from the Closing Date Term Loan to repay in full the Company’s then-existing indebtedness under its SVB Loan Agreement and to pay fees and expenses in connection with the foregoing and the Company intends to use the remainder of the proceeds for general corporate purposes.

Any indebtedness under the Term Loan Credit Agreement bears interest at a floating per annum rate equal to the LIBOR as reported by MidCap with a floor of 1.00%, which as of March 31, 2019 was 2.49%, plus 7.50%. The Term Loans have a scheduled maturity date of December 1, 2021, or the Maturity Date. Subject to an election to delay principal payments, the Company made monthly payments of accrued interest under the Term Loans from the funding date of the Term Loans, until December 31, 2018, to be followed by monthly installments of principal and interest through the Maturity Date. Under the terms of the Term Loan Credit Agreement, the Company had the option to extend the interest only period an additional six months to June 30, 2019 as long as the Company remains in compliance with the Term Loan Agreement. The Company has elected to extend the interest only period through June 30, 2019. The Company may prepay all of the Term Loans prior to its maturity date provided the Company pays MidCap a prepayment fee. The Company paid an origination fee of 0.50% of the Term Loans total amount of $40.0 million on the closing date. As of March 31, 2019, there was $35.0 million outstanding related to the Term Loans. As of March 31, 2019, the unamortized debt issuance costs on the Term Loans was approximately $0.1 million current portion and approximately $0.1 million long-term portion and are included as a reduction to debt on the condensed consolidated balance sheet.

Any indebtedness under the Revolving Credit Agreement bears interest at a floating per annum rate equal to the LIBOR as reported by MidCap with a floor of 1.00%, plus 4.50%. The Company may make and repay borrowings from time to time under the Revolving Credit Agreement until the maturity of the facility on December 1, 2021. The Company is required to pay an annual collateral management fee of 0.50% on the outstanding balance, and an annual unused line fee of 0.50% of the average unused portion. The Company paid an origination fee of 0.50% of the Revolving Loan amount of $10.0 million on the closing date. The Company classifies the amounts borrowed under the Revolving Loan as short term because it is the Company's intention to use the line of credit to borrow and pay back funds over short periods of time. As of March 31, 2019, there were $2.6 million borrowings outstanding under the Revolving Loan. As of March 31, 2019, the unamortized debt issuance costs related to the Revolving Loan was approximately $0.1 million and was included in other long-term assets on the condensed consolidated balance sheet.

The amortization of debt issuance costs for both the three months ended March 31, 2019 and 2018 was $0.1 million, and was included in interest expense in the condensed consolidated statements of operations.

The Credit Agreements include customary affirmative and restrictive covenants and representations and warranties, including a financial covenant for minimum revenues, a financial covenant for minimum cash requirements, a covenant against the occurrence of a “change in control,” financial reporting obligations, and certain limitations on indebtedness, liens, investments, distributions, collateral, mergers or acquisitions, taxes, and deposit accounts. Upon the occurrence of an event of default, a default interest rate of an additional 5.0% may be applied to any outstanding principal balances, and MidCap may declare all outstanding obligations immediately due and payable and take such other actions as set forth in the Credit Agreements. The Company’s obligations under the Credit Agreements are secured by a security interest in substantially all of The Company’s assets.

Future Principal Payments of Debt

The future schedule of principal payments for the outstanding Term Loans as of March 31, 2019 was as follows (in thousands):

Fiscal Year
Remainder of 2019	$	7,000
2020		14,000
2021		14,000
2022		—
2023		—
Thereafter		—
Total	$	35,000

Stockholders' Equity

3 Months Ended

Mar. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stockholders' Equity

11.	Stockholders’ Equity

a.

Authorized Stock

The Company’s Amended and Restated Certificate of Incorporation authorizes the Company to issue 210,000,000 shares of common and preferred stock, consisting of 200,000,000 shares of common stock with $0.01 par value and 10,000,000 shares of preferred stock with $0.01 par value. As of March 31, 2019 and December 31, 2018, the Company had no preferred stock issued or outstanding.

b.

Common Stock Warrants

On January 17, 2013, the Company entered into a Loan and Security Agreement, or the Original Term Loan Agreement, with Oxford Finance, LLC, or Oxford. On June 30, 2014, the Company entered into an Amended and Restated Loan and Security Agreement, or the Amended Term Loan Agreement, with Oxford. In connection with the Original Term Loan Agreement and the Amended Term Loan Agreement, the Company issued to Oxford (i) seven-year warrants in January 2013 to purchase shares of the Company’s common stock with a value equal to 3.0% of the tranche A, B and C term loans amounts and (ii) seven-year warrants in June 2014 to purchase shares of the Company’s common stock with a value equal to 2.5% of the tranche D term loan amount. The warrants have an exercise price per share of $14.671. As of March 31, 2019, there were warrants to purchase an aggregate of 47,710 shares of common stock outstanding.

c.

Stock Option Plans

In April 2007, the Company adopted the 2007 Equity Incentive Plan, or the 2007 Plan. The 2007 Plan provides for the granting of stock options to employees, directors and consultants of the Company. Options granted under the 2007 Plan may either be incentive stock options or nonstatutory stock options. Incentive stock options, or ISOs, may be granted only to Company employees. Nonstatutory stock options, or NSOs, may be granted to all eligible recipients. A total of 1,690,448 shares of the Company’s common stock were initially reserved for issuance under the 2007 Plan.

The Company’s board of directors adopted the 2014 Equity Incentive Plan, or 2014 Plan, in July 2014, and the stockholders approved the 2014 Plan in October 2014. The 2014 Plan became effective upon completion of the IPO on November 3, 2014, at which time the Company ceased granting awards under the 2007 Plan. Under the 2014 Plan, the Company may issue ISOs, NSOs, stock appreciation rights, restricted stock awards, restricted stock unit awards and other forms of stock awards, or collectively, stock awards, all of which may be granted to employees, including officers, non-employee directors and consultants of the Company and their affiliates. ISOs may be granted only to employees. A total of 1,027,500 shares of common stock were initially reserved for issuance under the 2014 Plan, subject to certain annual increases. As of March 31, 2019, a total of 1,346,169 shares of the Company’s common stock were available for issuance under the 2014 Plan.

Pursuant to a board-approved Inducement Plan, the Company may issue NSOs and restricted stock unit awards, or collectively, stock awards, all of which may only be granted to new employees of the Company and their affiliates in accordance with NASDAQ Stock Market Rule 5635(c)(4) as an inducement material to such individuals entering into employment with the Company. As of March 31, 2019, inducement grants for 1,019,211 shares of common stock have been awarded, and 35,984 shares of common stock were available for future issuance under the Inducement Plan.

Options under the 2007 Plan and the 2014 Plan may be granted for periods of up to ten years as determined by the Company’s board of directors, provided, however, that (i) the exercise price of an ISO shall not be less than 100% of the estimated fair value of the shares on the date of grant, and (ii) the exercise price of an ISO granted to a more than 10% shareholder shall not be less than 110% of the estimated fair value of the shares on the date of grant. An NSO has no such exercise price limitations. NSOs under the Inducement Plan may be granted for periods of up to ten years as determined by the board of directors, provided, the exercise price will not be less than 100% of the estimated fair value of the shares on the date of grant. Options generally vest with 25% of the grant vesting on the first anniversary and the balance vesting monthly on a straight-lined basis over the requisite service period of three additional years for the award. Additionally, options have been granted to certain key executives that vest upon achievement of performance conditions based on performance targets as defined by the board of directors, which have included net sales targets and defined corporate objectives over the performance period with possible payout ranging from 0% to 100% of the target award. Compensation expense is recognized on a straight-lined basis over the vesting term of one year based upon the probable performance target that will be met. The vesting provisions of individual options may vary but provide for vesting of at least 25% per year.

The following summarizes all option activity under the 2007 Plan, 2014 Plan and Inducement Plan:

				Weighted		Weighted average
				average		remaining
	Option			exercise		contractual
	Shares			price		term (year)
Balances at December 31, 2018		1,953,334		$	7.42		6.30
Exercised		(45,453	)		2.34
Balances at March 31, 2019		1,907,881		$	7.54		6.21

For stock-based awards the Company recognizes compensation expense based on the grant date fair value using the Black-Scholes option valuation model. Stock-based compensation expense related to stock options was $0.2 million and $0.4 million for the three months ended March 31, 2019 and 2018, respectively. As of March 31, 2019, there was $0.4 million of unrecognized compensation costs related to stock options. The expense is recorded within the operating expense components in the condensed consolidated statement of operations based on the recipients receiving the awards. These costs are expected to be recognized over a weighted average period of approximately 1 year.

d.

Restricted Stock Units

The Company has issued restricted stock unit awards, or RSUs, under the 2014 Plan and the Inducement Plan. The RSUs issued to employees generally vest on a straight-line basis annually over a 3-year requisite service period. RSUs issued to non-employees generally vest either monthly or annually over the service term.

Activity related to RSUs is set forth below:

				Weighted average
	Number			grant date
	of shares			fair value
Balances at December 31, 2018		2,141,350		$	13.27
Granted		170,508			11.37
Vested		(671,245	)		10.96
Forfeited		(102,206	)		19.48
Balances at March 31, 2019		1,538,407		$	13.65

Stock-based compensation expense for RSUs for the three months ended March 31, 2019 and 2018 was $3.4 million and $2.0 million, respectively. As of March 31, 2019, there was $16.1 million of total unrecognized compensation costs related to non-vested RSU awards. The cost is expected to be recognized over a weighted average period of approximately 2 years.

e.

Employee Stock Purchase Plan

The Company’s board of directors adopted the 2014 Employee Stock Purchase Plan, or ESPP, in July 2014, and the stockholders approved the ESPP in October 2014. The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. The ESPP provides for offering periods not to exceed 27 months, and each offering period will include purchase periods, which will be the approximately six-month period commencing with one exercise date and ending with the next exercise date. Employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the purchase date. A total of 255,500 shares of common stock were initially reserved for issuance under the ESPP, subject to certain annual increases.

During the three months ended March 31, 2019, employees purchased 68,899 shares of common stock at a weighted average price of $9.91 per share. As of March 31, 2019, the number of shares of common stock available for future issuance was 761,344.

The Company estimated the fair value of employee stock purchase rights using the Black-Scholes model. Stock-based compensation expense related to the ESPP was $0.2 million and $0.1 million for the three months ended March 31, 2019 and 2018, respectively.

a.

Significant Modifications

During the three months ended March 31, 2019 the Company entered into a consulting agreement with one former employee that resulted in the modification of their existing equity awards. During the three months ended March 31, 2019 the Company recognized $0.4 million in incremental compensation cost resulting from this modification.

Income Taxes

3 Months Ended

Mar. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

12.	Income Taxes

The Company operates in several tax jurisdictions and is subject to taxes in each jurisdiction in which it conducts business. To date, the Company has incurred cumulative net losses and maintains a full valuation allowance on its net deferred tax assets due to the uncertainty surrounding realization of such assets. The Company had no tax expense for both the three months ended March 31, 2019 and 2018.

Segment Information

3 Months Ended

Mar. 31, 2019

Segment Reporting [Abstract]

Segment Information

13.	Segment Information

Reportable Segments

The Company has two reportable segments: Breast Products and miraDry. The Breast Products segment focuses on sales of silicone gel breast implants, tissue expanders and scar management products under the brands Opus, AlloX2, Dermaspan, Softspan and BIOCORNEUM. The miraDry segment focuses on sales of the miraDry System, consisting of a console and a handheld device which uses consumable single-use bioTips. These segments align with the Company’s principal target markets.

The Company’s Chief Operating Decision Maker, or CODM, assesses the performance of each segment and allocates resources to those segments based on net sales and operating income (loss). Operating income (loss) by segment includes items that are directly attributable to each segment, including sales and marketing functions, as well as finance, information technology, human resources, legal and related corporate infrastructure costs, along with certain benefit-related expenses. There are no unallocated expenses for the two segments.

The following tables present the net sales, net operating loss and net assets by reportable segment for the periods presented (in thousands):

	March 31,
	2019		2018
Net sales
Breast Products	$	9,751	$	8,542
miraDry		7,801		6,134
Total net sales	$	17,552	$	14,676

	March 31,
	2019			2018
Loss from operations
Breast Products	$	(14,032	)	$	(12,794	)
miraDry		(11,819	)		(6,133	)
Total loss from operations	$	(25,851	)	$	(18,927	)

	March 31,		December 31,
	2019		2018
Assets
Breast Products	$	126,385	$	130,149
miraDry		45,240		38,210
Total assets	$	171,625	$	168,359

Commitments and Contingencies

3 Months Ended

Mar. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

14.	Commitments and Contingencies

The Company is subject to claims and assessment from time to time in the ordinary course of business. The Company accrues a liability for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated.

miraDry Class Action Litigation

On August 3, 2017, a lawsuit styled as a verified class action on the part of the former stockholders of miraDry was filed in the Court of Chancery for the State of Delaware against the former board of directors of miraDry, or the Defendants, alleging breach of their fiduciary duties in connection with the Company’s acquisition of miraDry. On August 30, 2017, the Defendants moved to dismiss the verified class action complaint for failure to state a claim upon which relief can be granted. On November 11, 2017 the parties notified the Court that they had reached an agreement to settle the matter pending completion of confirmatory discovery regarding the fairness of the settlement and obtaining approval from the court. Following a hearing, the Delaware Chancery Court approved the proposed settlement terms on January 15, 2019, with a modification to the amount of attorneys’ fees awarded to the plaintiffs’ attorneys. Under the terms of the settlement, in exchange for a full and final settlement and release of all claims, the Defendants (and/or their indemnitors and/or insurers) paid a settlement consideration of $0.4 million. The miraDry Merger Agreement contained a holdback amount expected to be used for the settlement and associated costs of the miraDry Class Action litigation. The holdback amount has been used to offset $0.6 million of legal fees and $0.4 million was included in “legal settlement payable” on the consolidated balance sheet as of December 31, 2018. As of March 31, 2019, the legal settlement of $0.4 million was paid.

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

Basis of Presentation

a.

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements in this Quarterly Report on Form 10-Q have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, and the rules and regulations of the U.S. Securities and Exchange Commission, or SEC. Accordingly, they do not include certain footnotes and financial presentations normally required under accounting principles generally accepted in the United States of America for complete financial reporting. The interim financial information is unaudited, but reflects all normal adjustments and accruals which are, in the opinion of management, considered necessary to provide a fair presentation for the interim periods presented. The accompanying condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 filed with the SEC on March 14, 2019, or the Annual Report. The results for the three months ended March 31, 2019 are not necessarily indicative of results to be expected for the year ending December 31, 2019, any other interim periods, or any future year or period.

Liquidity

b.

Liquidity

Since the Company’s inception, it has incurred significant net operating losses and the Company anticipates that losses will continue in the near term. The Company expects its operating expenses will continue to grow as they expand operations. The Company will need to generate significant net sales to achieve profitability. To date, the Company has funded operations primarily with proceeds from the sales of preferred stock, borrowings under term loans, sales of products since 2012, and the proceeds from the sale of common stock in public offerings.

The accompanying condensed consolidated financial statements have been prepared on a going concern basis, which implies the Company will continue to realize its assets and discharge its liabilities in the normal course of business. As of March 31, 2019, the Company had cash and cash equivalents of $62.0 million. Since inception, the Company has incurred recurring losses from operations and cash outflows from operating activities. The continuation of the Company as a going concern is dependent upon many factors including liquidity and the ability to raise capital. The Company received FDA approval of their PMA supplement on April 17, 2018 and was then able to access a $10.0 million term loan pursuant to an amendment to the credit agreement with MidCap Financial Trust, or MidCap. In addition, in February 2018, the Company entered into an At-The-Market Equity Offering Sales Agreement with Stifel, Nicolaus & Company, Incorporated, or Stifel, as sales agent pursuant to which the Company may sell, from time to time, through Stifel, shares of our common stock having an aggregate gross offering price of up to $50.0 million. As of March 31, 2019, the Company has not sold any common stock pursuant to the sales agreement. Further, on May 7, 2018, the Company completed a public offering of its common stock, raising approximately $107.6 million in net proceeds after deducting underwriting discounts and commissions and other offering expenses.

The Company believes that its cash and cash equivalents will be sufficient to fund its operations for at least the next 12 months. To fund ongoing operating and capital needs, the Company may need to raise additional capital in the future through the sale of equity securities and incremental debt financing.

Use of Estimates

c.

Use of Estimates

The preparation of the condensed consolidated financial statements, in conformity with GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates.

Significant Accounting Policies

d.

Significant Accounting Policies

Revenue Recognition

The Company recognizes revenue when the Company transfers control of promised goods or services to customers in an amount that reflects the consideration to which the Company expects to be entitled to in exchange for those goods or services. See Note 3 - Revenue for further discussion.

There have been no other changes to the accounting policies during the three months ended March 31, 2019, as compared to the significant accounting policies described in the “Notes to Financial Statements” in the Annual Report other than the adoption of Topic 842, as discussed in “Recent Accounting Pronouncements” and Note 9.

Recent Accounting Pronouncements

e.

Recent Accounting Pronouncements

Recently Adopted Accounting Standards

In February 2016, the FASB issued Accounting Standards Update, or ASU, 2016-02, Leases (Topic 842). This ASU requires a company to recognize lease assets and liabilities arising from operating leases in the statement of financial position. This ASU does not significantly change the previous lease guidance for how a lessee should recognize the recognition, measurement, and presentation of expenses and cash flows arising from a lease. Additionally, the criteria for classifying a finance lease versus an operating lease are substantially the same as the previous guidance. This ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and early adoption was permitted. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842) Targeted Improvements, amending certain aspects of the new leasing standard. The amendment allowed an additional optional transition method whereby an entity records a cumulative effect adjustment to opening retained earnings in the year of adoption without restating prior periods. The Company adopted Topic 842 on January 1, 2019 electing the package of practical expedients permitted under the transition guidance, which allowed the Company to carry forward the historical lease classification, the assessment on whether a contract is or contains a lease, and the initial direct costs for any leases that exist prior to adoption of the new standard. The Company has not restated prior periods under the optional transition method. The adoption of ASU 2016-02 on January 1, 2019 resulted in the recognition of right-of-use assets of approximately $22.7 million, lease liabilities of approximately $22.9 million and no cumulative-effect adjustment on retained earnings on its Condensed Consolidated Balance Sheets. Refer to Note 9 - Leases for further details.

In February 2018, the FASB issued ASU 2018-02, Income Taxes (Topic 740), which allows for an entity to elect to reclassify the income tax effects on items within accumulated other comprehensive income resulting from U.S. Tax Cuts and Jobs Act to retained earnings. The guidance is effective for fiscal years beginning after December 15, 2018 with early adoption permitted, including interim periods within those years. The Company adopted ASC 2018-02 and elected to not reclassify the income tax effects under ASU 2018-02, as it does not have a material impact on the condensed consolidated financial statements.

Reclassifications

f.

Reclassifications

Certain reclassifications have been made to prior year amounts to conform to the current year presentation.

Revenue Recognition

The Company generates revenue primarily through the sale and delivery of promised goods or services to customers and recognizes revenue when control is transferred to customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for the goods or services. Performance obligations typically include the delivery of promised products, such as breast implants, tissue expanders, BIOCORNEUM, miraDry Systems and bioTips, along with service-type warranties and deliverables under certain marketing programs. Other deliverables are sometimes promised, but are ancillary and insignificant in the context of the contract as a whole. Sales prices are documented in the executed sales contract, purchase order or order acknowledgement prior to the transfer of control to the customer. Customers may enter into a separate extended service agreement to purchase an extended warranty for miraDry products from the Company whereby the payment is due at the inception of the agreement. Typical payment terms are 30 days for Breast Products and direct sales of consumable miraDry products, and tend to be longer for capital sales of miraDry Systems and sales to miraDry distributors, but do not extend beyond one year. For delivery of promised products, control transfers and revenue is recognized upon shipment, unless the contractual arrangement requires transfer of control when products reach their destination, for which revenue is recognized once the product arrives at its destination. Revenue for extended service agreements are recognized ratably over the term of the agreements.

For Breast Products, with the exception of the Company’s BIOCORNEUM scar management products, the Company allows for the return of products from customers within six months after the original sale, which is accounted for as variable consideration. Reserves are established for anticipated sales returns based on the expected amount calculated with historical experience, recent gross sales and any notification of pending returns. The estimated sales return is recorded as a reduction of revenue and as a sales return liability in the same period revenue is recognized. Actual sales returns in any future period are inherently uncertain and thus may differ from the estimates. If actual sales returns differ significantly from the estimates, an adjustment to revenue in the current or subsequent period would be recorded. The Company has established an allowance for sales returns of $8.0 million and $6.0 million as of March 31, 2019 and December 31, 2018 respectively, recorded as “sales return liability” on the condensed consolidated balance sheets.

The following table provides a rollforward of the sales return liability (in thousands):

	Sales return liability
Balance as of December 31, 2018	$	6,048
Addition to reserve for sales activity		22,617
Actual returns		(21,040	)
Change in estimate of sales returns		391
Balance as of March 31, 2019	$	8,016

For Breast Products, a portion of the Company’s revenue is generated from the sale of consigned inventory of breast implants maintained at doctor, hospital, and clinic locations. For these products, revenue is recognized at the time the Company is notified by the customer that the product has been implanted, not when the consigned products are delivered to the customer’s location.

For miraDry, in addition to domestic and international direct sales, the Company leverages a distributor network for selling the miraDry System internationally. The Company recognizes revenue when control of the goods or services is transferred to the distributors. Standard terms in both direct sales agreements (domestic and international), and international distributor agreements do not allow for trial periods, right of return, refunds, payment contingent on obtaining financing or other terms that could impact the customer’s payment obligation.

Arrangements with Multiple Performance Obligations

The Company has determined that the delivery of each unit of product in the Company’s revenue contracts with customers is a separate performance obligation. The Company’s revenue contracts may include multiple products or services, each of which is considered a separate performance obligation. For such arrangements, the Company allocates revenue to each performance obligation based on its relative standalone selling price. The Company generally determines standalone selling prices based on observable prices or using an expected cost plus margin approach when an observable price is not available. The Company invoices customers once products are shipped or delivered to customers depending on the negotiated shipping terms.

The Company introduced its Platinum20 Limited Warranty Program, or Platinum20, in May 2018 on all OPUS breast implants implanted in the United States or Puerto Rico on or after May 1, 2018. Platinum20 provides for financial assistance for revision surgeries and no-charge contralateral replacement implants upon the occurrence of certain qualifying events. The Company considers Platinum20 to have an assurance warranty component and a service warranty component. The assurance component is recorded as a warranty liability at the time of sale (as discussed in Note 6). The Company considers the service warranty component as an additional performance obligation and defers revenue at the time of sale based on the relative estimated selling price, by estimating a standalone selling price using the expected cost plus margin approach for the performance obligation. Inputs into the expected cost plus margin approach include historical incidence rates, estimated replacement costs, estimated financial assistance payouts and an estimated margin. The liability for unsatisfied performance obligations under the service warranty as of March 31, 2019 and December 31, 2018 was $0.6 million and $0.4 million respectively. The short-term obligation related to the service warranty as of both March 31, 2019 and December 31, 2018 was $0.2 million and is included in “accrued and other current liabilities” on the condensed consolidated balance sheets. The long-term obligation related to the service warranty as of both March 31, 2019 and December 31, 2018 was $0.3 million, and is included in “warranty reserve and other long-term liabilities” on the condensed consolidated balance sheets. The performance obligation is satisfied at the time that Platinum20 benefits are provided and are expected to be satisfied over the following 6 to 24 month period for financial assistance and 20 years for product replacement. Revenue recognized for the service warranty performance obligations for the three months ended March 31, 2019 was immaterial.

Practical Expedients and Policy Election

The Company generally expenses sales commissions when incurred because the amortization period would have been one year or less. These costs are recorded within sales and marketing expenses.

The Company does not adjust accounts receivable for the effects of any significant financing components as customer payment terms are shorter than one year.

The Company has elected to account for shipping and handling activities performed after a customer obtains control of the products as activities to fulfill the promise to transfer the products to the customer. Shipping and handling activities are largely provided to customers free of charge for the Breast Products segment. The associated costs were $0.4 million and $0.2 million for the three months ended March 31, 2019 and 2018 respectively. These costs are viewed as part of the Company’s sales and marketing programs and are recorded as a component of sales and marketing expense in the condensed consolidated statement of operations as an accounting policy election. For the miraDry segment, shipping and handling charges are typically billed to customers and recorded as revenue. The shipping and handling costs incurred are recorded as a component of cost of goods sold in the condensed consolidated statement of operations. The associated costs were $0.1 million for both the three months ended March 31, 2019 and 2018.

Leases

The Company leases certain office space, warehouses, distribution facilities and office equipment. The Company also has embedded leases of manufacturing facilities and equipment associated with the Company’s manufacturing contracts. The Company determines if an arrangement contains a lease at inception by evaluating whether the arrangement conveys the right to use an identified asset and whether the Company obtains substantially all of the economic benefits from and has the ability to direct the use of the asset.

Operating and finance lease right-of-use, or ROU, assets and lease liabilities are recognized based on the present value of the future lease payments over the lease term at the commencement date. The Company determines its incremental borrowing rate based on the information available at the commencement date in determining the lease liabilities as the Company’s leases generally do not provide an implicit rate. The ROU assets also include any initial direct costs incurred and any lease payments made at or before the lease commencement date, less lease incentives received. Lease terms may include options to extend or terminate when the Company is reasonably certain that the option will be exercised. The Company elected to apply the short-term lease measurement and recognition exemption in which ROU assets and lease liabilities are not recognized for short-term leases. The Company’s lease agreements generally do not contain material residual value guarantees or material restrictive covenants.

The Company’s leases of office space, warehouses and distribution facilities are treated as operating leases and often contain lease and non-lease components. The Company has elected to account for these lease and non-lease components separately. Non-lease components for these assets are primarily comprised of common-area maintenance, utilities, and real estate taxes that are passed on from the lessor in proportion to the space leased by the Company, and are recognized in operating expenses in the period in which the obligation for those payments was incurred. Lease cost for these operating leases is recognized on a straight-line basis over the lease term in operating expenses.

The Company’s embedded leases of manufacturing facilities and equipment are treated as operating leases and often contain lease and non-lease components. The Company has elected to account for these lease and non-lease components as a single lease component. There may be variability in future lease payments as the amount of the non-lease components is based on the costs of manufacturing and is dependent on the amount and types of units produced. The Company reduces the operating lease liability when the inventory is purchased.

The Company’s leases of office equipment are accounted for as finance leases as they meet one or more of the five finance lease classification criteria. Lease cost for these finance leases is comprised of amortization of the ROU asset and interest expense which are recognized in operating expenses and other income (expense), net.

Revenue (Tables)

3 Months Ended

Mar. 31, 2019

Revenue Recognition [Abstract]

Schedule of Rollforward of Sales Return Liability

The following table provides a rollforward of the sales return liability (in thousands):

	Sales return liability
Balance as of December 31, 2018	$	6,048
Addition to reserve for sales activity		22,617
Actual returns		(21,040	)
Change in estimate of sales returns		391
Balance as of March 31, 2019	$	8,016

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of Company's Liabilities that are Measured at Fair Value on a Recurring Basis

The following tables present information about the Company’s liabilities that are measured at fair value on a recurring basis as of March 31, 2019 and December 31, 2018 and indicate the level of the fair value hierarchy utilized to determine such fair value (in thousands):

	Fair Value Measurements as of
	March 31, 2019 Using:
	Level 1		Level 2		Level 3		Total
Liabilities:
Liability for common stock warrants	$	—		—		26		26
Liability for contingent consideration		—		—		13,032		13,032
	$	—		—		13,058		13,058

	Fair Value Measurements as of
	December 31, 2018 Using:
	Level 1		Level 2		Level 3		Total
Liabilities:
Liability for common stock warrants	$	—		—		113		113
Liability for contingent consideration		—		—		13,847		13,847
	$	—		—		13,960		13,960

Schedule of Aggregate Fair Values of the Company's Common Stock Warrants and Contingent Consideration for which Fair Value is Determined by Level 3 Inputs

The following table provides a rollforward of the aggregate fair values of the Company’s common stock warrants and contingent consideration for which fair value is determined by Level 3 inputs (in thousands):

Warrant Liability
Balance, December 31, 2018	$	113
Change in fair value of warrant liability		(87	)
Balance, March 31, 2019	$	26
Contingent Consideration Liability
Balance, December 31, 2018	$	13,847
Payments of contingent consideration		(1,000	)
Change in fair value of contingent consideration		185
Balance, March 31, 2019	$	13,032

Product Warranties (Tables)

3 Months Ended

Mar. 31, 2019

Product Warranties Disclosures [Abstract]

Schedule of rollforward of the accrued warranties

The following table provides a rollforward of the accrued warranties (in thousands):

	Three Months Ended March 31,
	2019			2018
Beginning balance as of January 1	$	1,395		$	1,642
Warranty costs incurred during the period		(139	)		(104	)
Changes in accrual related to warranties issued during the period		244			50
Changes in accrual related to pre-existing warranties		29			133
Balance as of March 31	$	1,529		$	1,721

Net Loss Per Share (Tables)

3 Months Ended

Mar. 31, 2019

Earnings Per Share [Abstract]

Schedule of net loss per share, basic and diluted

	Three Months Ended March 31,
	2019			2018
Net loss (in thousands)	$	(26,484	)	$	(19,423	)
Weighted average common shares outstanding, basic and diluted		29,099,382			19,613,417
Net loss per share attributable to common stockholders	$	(0.91	)	$	(0.99	)

Schedule of potentially dilutive securities excluded from the computation of diluted net loss per share attributable to common stockholders

The Company excluded the following potentially dilutive securities, outstanding as of March 31, 2019 and 2018, from the computation of diluted net loss per share attributable to common stockholders for the three months ended March 31, 2019 and 2018 because they had an anti-dilutive impact due to the net loss attributable to common stockholders incurred for the periods.

	March 31,
	2019		2018
Stock options to purchase common stock		1,469,792		1,600,826
Warrants for the purchase of common stock		47,710		47,710
		1,517,502		1,648,536

Balance Sheet Components (Tables)

3 Months Ended

Mar. 31, 2019

Balance Sheet Related Disclosures [Abstract]

Schedule of inventories, net

Inventories, net consist of the following (in thousands):

	March 31,		December 31,
	2019		2018
Raw materials	$	2,680	$	2,147
Work in progress		2,690		2,110
Finished goods		19,850		18,335
Finished goods - right of return		2,022		1,493
	$	27,242	$	24,085

Schedule of property and equipment, net

Property and equipment, net consist of the following (in thousands):

	March 31,			December 31,
	2019			2018
Leasehold improvements	$	402		$	402
Manufacturing equipment and toolings		2,463			1,928
Computer equipment		748			682
Software		1,213			1,039
Office equipment		117			156
Furniture and fixtures		934			826
		5,877			5,033
Less accumulated depreciation		(2,731	)		(2,497	)
	$	3,146		$	2,536

Schedule of changes in carrying amount of goodwill

The changes in the carrying amount of goodwill during the three months ended March 31, 2019 were as follows (in thousands):

	Breast Products			miraDry		Total
Balances as of December 31, 2018
Goodwill	$	19,156		$	7,629	$	26,785
Accumulated impairment losses		(14,278	)		—		(14,278	)
Goodwill, net	$	4,878		$	7,629	$	12,507

Balances as of March 31, 2019
Goodwill	$	19,156		$	7,629	$	26,785
Accumulated impairment losses		(14,278	)		—		(14,278	)
Goodwill, net	$	4,878		$	7,629	$	12,507

Schedule of intangible assets

The components of the Company’s other intangible assets consist of the following (in thousands):

	Average
	Amortization		March 31, 2019
	Period		Gross Carrying		Accumulated			Intangible
	(in years)		Amount		Amortization			Assets, net
Intangibles with definite lives
Customer relationships		11	$	11,240	$	(3,878	)	$	7,362
Trade names - finite life		14		5,800		(638	)		5,162
Developed technology		15		3,000		(407	)		2,593
Distributor relationships		9		500		(152	)		348
Non-compete agreement		2		80		(80	)		—
Regulatory approvals		1		670		(670	)		—
Acquired FDA non-gel product approval		11		1,713		(1,713	)		—
Total definite-lived intangible assets			$	23,003	$	(7,538	)	$	15,465

Intangibles with indefinite lives
Trade names - indefinite life	—			450		—			450
Total indefinite-lived intangible assets			$	450	$	—		$	450

	Average
	Amortization		December 31, 2018
	Period		Gross Carrying		Accumulated			Intangible
	(in years)		Amount		Amortization			Assets, net
Intangibles with definite lives
Customer relationships		11	$	11,240	$	(3,486	)	$	7,754
Trade names - finite life		14		5,800		(541	)		5,259
Developed technology		15		3,000		(338	)		2,662
Distributor relationships		9		500		(130	)		370
Non-compete agreement		2		80		(80	)		—
Regulatory approvals		1		670		(670	)		—
Acquired FDA non-gel product approval		11		1,713		(1,713	)		—
Total definite-lived intangible assets			$	23,003	$	(6,958	)	$	16,045

Intangibles with indefinite lives
Trade names - indefinite life	—			450		—			450
Total indefinite-lived intangible assets			$	450	$	—		$	450

Schedule of estimated amortization expense

The following table summarizes the estimated amortization expense relating to the Company's definite-lived intangible assets as of March 31, 2019 (in thousands):

	Amortization
Period	Expense
Remainder of 2019	$	1,741
2020		2,209
2021		1,996
2022		1,762
2023		1,545
Thereafter		6,212
	$	15,465

Schedule of accrued and other current liabilities

Accrued and other current liabilities consist of the following (in thousands):

	March 31,		December 31,
	2019		2018
Payroll and related expenses	$	4,561	$	6,466
Accrued commissions		4,175		5,321
Accrued equipment		427		18
Deferred and contingent consideration, current portion		6,780		7,645
Audit, consulting and legal fees		2,267		703
Accrued sales and marketing expenses		2,157		1,374
Operating lease liabilities		4,707		—
Finance lease liabilities		42		—
Other		5,300		6,170
	$	30,416	$	27,697

Leases (Tables)

3 Months Ended

Mar. 31, 2019

Leases [Abstract]

Components of Lease Expense

Components of lease expense were as follows:

		Three Months Ended March 31,
Lease Cost	Classification	2019
Operating lease cost	Operating expenses	$	380
Operating lease cost	Inventory		1,248
Total operating lease cost		$	1,628
Finance lease cost
Amortization of right-of-use assets	Operating expenses		9
Interest on lease liabilities	Other income (expense), net		1
Total finance lease cost		$	10
Variable lease cost	Inventory		2,373
Total lease cost		$	4,011

Supplemental Cash Flow Information Related to Operating and Finance Leases

Supplemental cash flow information related to operating and finance leases for the three months ended March 31, 2019 was as follows (in thousands):

	Three Months Ended March 31,
	2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflows from operating leases	$	1,462
Operating cash outflows from finance leases		9
Right-of-use assets obtained in exchange for new lease obligations:
Operating leases	$	23,046
Finance leases		119

Supplemental Balance Sheet Information Related to Operating and Finance Leases

Supplemental balance sheet information, as of March 31, 2019, related to operating and finance leases was as follows (in thousands, except lease term and discount rate):

	March 31,
	2019
Reported as:
Other assets
Operating lease right-of-use assets	$	21,885
Finance lease right-of-use assets		111
Total right-of use assets	$	21,996
Accrued and other current liabilities
Operating lease liabilties	$	4,707
Finance lease liabilities		42
Warranty reserve and other long-term liabilities
Operating lease liabilties		17,548
Finance lease liabilities		66
Total lease liabilities	$	22,363
Weighted average remaining lease term (years)
Operating leases		4
Finance leases		3
Weighted average discount rate
Operating leases		8.19	%
Finance leases		4.28	%

Maturities of Operating and Finance Lease Liabilities

As of March 31, 2019, maturities of the Company’s operating and finance lease liabilities are as follows (in thousands):

Period	Operating leases		Finance leases		Total
Remainder of 2019	$	4,795	$	35	$	4,830
2020		6,245		43		6,288
2021		6,242		36		6,278
2022		5,976		—		5,976
2023		2,654		—		2,654
2024 and thereafter		499		—		499
Total lease payments	$	26,411	$	114	$	26,525
Less imputed interest		4,156		6		4,162
Total operating lease liabilities	$	22,255	$	108	$	22,363

Schedule of Future Minimum Lease Payments under Non-cancelable Operating Leases

As previously reported in our Annual Report on Form 10-K for the year ended December 31, 2018 and under legacy lease accounting (ASC 840), future minimum lease payments under non-cancellable leases as of December 31, 2018 was as follows (in thousands):

Year Ended December 31:
2020	$	1,325
2021		1,134
2022		1,060
2023		947
2024 and thereafter		1,557
	$	6,023

Long-Term Debt and Revolving Loan (Tables)

3 Months Ended

Mar. 31, 2019

Debt Disclosure [Abstract]

Schedule of Future Principal Payments for Outstanding Term Loans

The future schedule of principal payments for the outstanding Term Loans as of March 31, 2019 was as follows (in thousands):

Fiscal Year
Remainder of 2019	$	7,000
2020		14,000
2021		14,000
2022		—
2023		—
Thereafter		—
Total	$	35,000

Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of option activity

The following summarizes all option activity under the 2007 Plan, 2014 Plan and Inducement Plan:

				Weighted		Weighted average
				average		remaining
	Option			exercise		contractual
	Shares			price		term (year)
Balances at December 31, 2018		1,953,334		$	7.42		6.30
Exercised		(45,453	)		2.34
Balances at March 31, 2019		1,907,881		$	7.54		6.21

Summary of RSUs activity

Activity related to RSUs is set forth below:

				Weighted average
	Number			grant date
	of shares			fair value
Balances at December 31, 2018		2,141,350		$	13.27
Granted		170,508			11.37
Vested		(671,245	)		10.96
Forfeited		(102,206	)		19.48
Balances at March 31, 2019		1,538,407		$	13.65

Segment Information (Tables)

3 Months Ended

Mar. 31, 2019

Segment Reporting [Abstract]

Summary of Net Sales, Net Operating Loss and Net Assets by Reportable Segment

The following tables present the net sales, net operating loss and net assets by reportable segment for the periods presented (in thousands):

	March 31,
	2019		2018
Net sales
Breast Products	$	9,751	$	8,542
miraDry		7,801		6,134
Total net sales	$	17,552	$	14,676

	March 31,
	2019			2018
Loss from operations
Breast Products	$	(14,032	)	$	(12,794	)
miraDry		(11,819	)		(6,133	)
Total loss from operations	$	(25,851	)	$	(18,927	)

	March 31,		December 31,
	2019		2018
Assets
Breast Products	$	126,385	$	130,149
miraDry		45,240		38,210
Total assets	$	171,625	$	168,359

Formation and Business of the Company (Details) $ / shares in Units, $ in Millions	May 07, 2018 USD ($) $ / shares shares
Formation And Business Of Company [Line Items]
Proceeds from the issuance of common stock, net of underwriting discounts, commissions and offering expenses	$ 107.6
Underwritten Follow-On Offering \| Common stock
Formation And Business Of Company [Line Items]
Shares issued in follow-on public offering \| shares	7,407,408
Public offering price (in dollars per share) \| $ / shares	$ 13.50
Additional shares granted to underwriters \| shares	1,111,111
Proceeds from the issuance of common stock, net of underwriting discounts, commissions and offering expenses	$ 107.6
Payment of underwriting discounts and commissions and offering expenses	6.9
Offering expenses	$ 0.5

Summary of Significant Accounting Policies (Details) - USD ($)			1 Months Ended
	Jan. 01, 2019	May 07, 2018	Feb. 28, 2018	Mar. 31, 2019	Dec. 31, 2018	Apr. 30, 2018	Apr. 17, 2018	Mar. 31, 2018
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents				$ 61,955,000	$ 86,899,000			$ 16,059,000
Common stock, shares issued				29,274,377	28,701,494
Proceeds from the issuance of common stock, net of underwriting discounts, commissions and offering expenses		$ 107,600,000
Right-of-use asset				$ 21,885,000
Lease, liabilities				$ 22,255,000
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment	$ 0
Right-of-use asset	22,700,000
Lease, liabilities	$ 22,900,000
At-The-Market Equity Offering Sales Agreement
Summary Of Significant Accounting Policies [Line Items]
Common stock, shares issued				0
Maximum
Summary Of Significant Accounting Policies [Line Items]
Aggregate gross offering price			$ 50,000,000
March Two Thousand Eighteen Term Loan
Summary Of Significant Accounting Policies [Line Items]
Loan amount outstanding						$ 10,000,000	$ 10,000,000

Revenue (Details 1) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-04-01	Mar. 31, 2019
Product Replacement
Revenue From Contracts With Customers [Line Items]
Performance obligation satisfying period	20 years
Maximum \| Financial Assistance
Revenue From Contracts With Customers [Line Items]
Performance obligation satisfying period	24 months
Minimum \| Financial Assistance
Revenue From Contracts With Customers [Line Items]
Performance obligation satisfying period	6 months
Breast Products and Consumable miraDry products \| Maximum
Revenue From Contracts With Customers [Line Items]
Performance obligation satisfying period	30 days
MiraDry Systems \| Maximum
Revenue From Contracts With Customers [Line Items]
Performance obligation satisfying period	1 year

Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Revenue (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Revenue From Contracts With Customers [Line Items]
Period for sales return	6 months
Allowance for sales returns	$ 8,000		$ 6,000
Liability for service warranty	$ 600		400
Revenue, practical expedient, incremental cost of obtaining contract	true
Revenue, practical expedient, significant financing component	true
Shipping and handling costs	$ 6,474	$ 6,097
Breast Products \| Sales and marketing expense
Revenue From Contracts With Customers [Line Items]
Shipping and handling costs	$ 400	$ 200
Type of Cost, Good or Service [Extensible List]	us-gaap:ShippingAndHandlingMember	us-gaap:ShippingAndHandlingMember
miraDry \| Cost of goods sold
Revenue From Contracts With Customers [Line Items]
Shipping and handling costs	$ 100	$ 100
Type of Cost, Good or Service [Extensible List]	us-gaap:ShippingAndHandlingMember	us-gaap:ShippingAndHandlingMember
Accrued and Other Current Liabilities
Revenue From Contracts With Customers [Line Items]
Short-term obligation	$ 200		200
Warranty Reserve and Other Long-term Liabilities
Revenue From Contracts With Customers [Line Items]
Long-term obligation	$ 300		$ 300

Revenue (Schedule of Rollforward of Sales Return Liability) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Revenue Recognition [Abstract]
Balance as of December 31, 2018	$ 6,048
Addition to reserve for sales activity	22,617
Actual returns	(21,040)
Change in estimate of sales returns	391
Balance as of March 31, 2019	$ 8,016

Fair Value Measurements (Details)	Mar. 31, 2019
Estimated Dividend Yield
Fair Value Measurements
Measurement input	0.00

Fair Value Measurements - Schedule of Company's Liabilities that are Measured at Fair Value on a Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value Measurements
Fair value liability	$ 13,058	$ 13,960
Warrants
Fair Value Measurements
Fair value liability	26	113
Contingent Consideration Liability
Fair Value Measurements
Fair value liability	13,032	13,847
Level 3
Fair Value Measurements
Fair value liability	13,058	13,960
Level 3 \| Warrants
Fair Value Measurements
Fair value liability	26	113
Level 3 \| Contingent Consideration Liability
Fair Value Measurements
Fair value liability	$ 13,032	$ 13,847

Fair Value Measurements - Schedule of Aggregate Fair Values of the Company's Common Stock Warrants and Contingent Consideration for which Fair Value is Determined by Level 3 Inputs (Details) - Level 3 - Recurring $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Warrants
Fair values of the Company's liabilities determined by Level 3 inputs
Balance at beginning of the period	$ 113
Change in fair value	(87)
Balance at the end of the period	26
Contingent Consideration Liability
Fair values of the Company's liabilities determined by Level 3 inputs
Balance at beginning of the period	13,847
Payments of contingent consideration	(1,000)
Change in fair value	185
Balance at the end of the period	$ 13,032

Product Warranties (Details) - USD ($)	3 Months Ended
Product Warranties (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Product Warranty Liability [Line Items]
Replacement implants and revision surgery financial assistance under limited warranty program	$ 1,529,000	$ 1,395,000	$ 1,721,000	$ 1,642,000
Implants occurring prior to May 1, 2018
Product Warranty Liability [Line Items]
Period to claim financial assistance under limited warranty program	10 years
Implants occurring prior to May 1, 2018 \| Maximum
Product Warranty Liability [Line Items]
Replacement implants and revision surgery financial assistance under limited warranty program	$ 3,600
Implants occurring on or after May 1, 2018
Product Warranty Liability [Line Items]
Period to claim financial assistance under limited warranty program	20 years
Implants occurring on or after May 1, 2018 \| Maximum
Product Warranty Liability [Line Items]
Replacement implants and revision surgery financial assistance under limited warranty program	$ 5,000

Product Warranties - Schedule of rollforward of the accrued warranties (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Product Warranties Disclosures [Abstract]
Beginning balance	$ 1,395	$ 1,642
Warranty costs incurred during the period	(139)	(104)
Changes in accrual related to warranties issued during the period	244	50
Changes in accrual related to pre-existing warranties	29	133
Ending Balance	$ 1,529	$ 1,721

Net Loss Per Share - Schedule of Net Loss Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net loss	$ (26,484)	$ (19,423)
Weighted average common shares outstanding, basic and diluted	29,099,382	19,613,417
Net loss per share attributable to common stockholders	$ (0.91)	$ (0.99)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Net Loss Per Share - Schedule of Potentially Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Potentially dilutive securities
Potentially dilutive securities	1,517,502	1,648,536
Stock options to purchase common stock
Potentially dilutive securities
Potentially dilutive securities	1,469,792	1,600,826
Warrants for the purchase of common stock
Potentially dilutive securities
Potentially dilutive securities	47,710	47,710

Balance Sheet Components (Allowance) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Allowance for doubtful accounts	$ 2.7	$ 2.4

Balance Sheet Components (Inventories) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Raw materials	$ 2,680	$ 2,147
Work in progress	2,690	2,110
Finished goods	19,850	18,335
Finished goods - right of return	2,022	1,493
Inventory, net	$ 27,242	$ 24,085

Balance Sheet Components (PPE) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Sep. 30, 2018
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 5,877		$ 5,033
Less accumulated depreciation	(2,731)		(2,497)
Property and equipment, net	3,146		2,536
Depreciation expense	300	$ 300
Repurchase equipment				$ 2,700
Leasehold improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	402		402
Manufacturing equipment and toolings
Property Plant And Equipment [Line Items]
Property and equipment, gross	2,463		1,928
Computer equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	748		682
Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,213		1,039
Office equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	117		156
Furniture and fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 934		$ 826

Balance Sheet Components (Goodwill and Intangibles) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Goodwill and intangible assets
Goodwill	$ 26,785		$ 26,785
Accumulated impairment losses	(14,278)		(14,278)
Goodwill, net	12,507		12,507
Other intangible assets
Gross Carrying Amount	23,003		23,003
Accumulated Amortization	(7,538)		(6,958)
Intangible Assets, net	15,465		16,045
Indefinite-lived intangible assets	450		450
Amortization expense	600	$ 600
Estimated amortization expense
Remainder of 2019	1,741
2020	2,209
2021	1,996
2022	1,762
2023	1,545
Thereafter	6,212
Total amortization	15,465
Trade name
Other intangible assets
Indefinite-lived intangible assets	$ 450		$ 450
Acquired FDA non-gel product approval
Other intangible assets
Average Amortization Period	11 years		11 years
Gross Carrying Amount	$ 1,713		$ 1,713
Accumulated Amortization	$ (1,713)		$ (1,713)
Customer relationships
Other intangible assets
Average Amortization Period	11 years		11 years
Gross Carrying Amount	$ 11,240		$ 11,240
Accumulated Amortization	(3,878)		(3,486)
Intangible Assets, net	$ 7,362		$ 7,754
Trade name
Other intangible assets
Average Amortization Period	14 years		14 years
Gross Carrying Amount	$ 5,800		$ 5,800
Accumulated Amortization	(638)		(541)
Intangible Assets, net	$ 5,162		$ 5,259
Developed technology
Other intangible assets
Average Amortization Period	15 years		15 years
Gross Carrying Amount	$ 3,000		$ 3,000
Accumulated Amortization	(407)		(338)
Intangible Assets, net	$ 2,593		$ 2,662
Distributor relationships
Other intangible assets
Average Amortization Period	9 years		9 years
Gross Carrying Amount	$ 500		$ 500
Accumulated Amortization	(152)		(130)
Intangible Assets, net	$ 348		$ 370
Regulatory approvals
Other intangible assets
Average Amortization Period	1 year		1 year
Gross Carrying Amount	$ 670		$ 670
Accumulated Amortization	$ (670)		$ (670)
Non-compete agreement
Other intangible assets
Average Amortization Period	2 years		2 years
Gross Carrying Amount	$ 80		$ 80
Accumulated Amortization	(80)		(80)
Breast Products
Goodwill and intangible assets
Goodwill	19,156		19,156
Accumulated impairment losses	(14,278)		(14,278)
Goodwill, net	4,878		4,878
miraDry
Goodwill and intangible assets
Goodwill	7,629		7,629
Goodwill, net	$ 7,629		$ 7,629

Balance Sheet Components (Accrued liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accrued and other current liabilities
Payroll and related expenses	$ 4,561	$ 6,466
Accrued commissions	4,175	5,321
Accrued equipment	427	18
Deferred and contingent consideration, current portion	6,780	7,645
Audit, consulting and legal fees	2,267	703
Accrued sales and marketing expenses	2,157	$ 1,374
Operating lease liabilities	$ 4,707
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	sien:AccruedAndOtherCurrentLiabilitiesMember	sien:AccruedAndOtherCurrentLiabilitiesMember
Finance lease liabilities	$ 42
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	sien:AccruedAndOtherCurrentLiabilitiesMember	sien:AccruedAndOtherCurrentLiabilitiesMember
Other	$ 5,300	$ 6,170
Total	$ 30,416	$ 27,697

Leases - Components of Lease Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Lessee Lease Description [Line Items]
Total operating lease cost	$ 1,628
Finance lease cost
Total finance lease cost	10
Total lease cost	4,011
Inventory
Lessee Lease Description [Line Items]
Total operating lease cost	1,248
Finance lease cost
Variable lease cost	2,373
Operating Expenses
Lessee Lease Description [Line Items]
Total operating lease cost	380
Finance lease cost
Amortization of right-of-use assets	9
Other Income (Expense), Net
Finance lease cost
Interest on lease liabilities	$ 1

Leases - Supplemental Cash Flow Information Related to Operating and Finance Leases (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflows from operating leases	$ 1,462
Operating cash outflows from finance leases	9
Right-of-use assets obtained in exchange for new lease obligations:
Operating leases	23,046
Finance leases	$ 119

Leases - Supplemental Balance Sheet Information Related to Operating and Finance Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets And Liabilities Lessee [Abstract]
Operating lease right-of-use assets	$ 21,885
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsMember
Finance lease right-of-use assets	$ 111
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsMember
Total right-of use assets	$ 21,996
Operating lease liabilities	$ 4,707
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	sien:AccruedAndOtherCurrentLiabilitiesMember	sien:AccruedAndOtherCurrentLiabilitiesMember
Finance lease liabilities	$ 42
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	sien:AccruedAndOtherCurrentLiabilitiesMember	sien:AccruedAndOtherCurrentLiabilitiesMember
Operating lease liabilties	$ 17,548
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	sien:WarrantyReserveAndOtherLongTermLiabilitiesMember
Finance lease liabilities	$ 66
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	sien:WarrantyReserveAndOtherLongTermLiabilitiesMember
Total lease liabilities	$ 22,363
Weighted average remaining lease term (years)
Operating leases	4 years
Finance leases	3 years
Weighted average discount rate
Operating leases	8.19%
Finance leases	4.28%

Leases - Maturities of Operating and Finance Lease Liabilities (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Operating Lease Liabilities, Payments Due [Abstract]
Operating leases, Remainder of 2019	$ 4,795
Operating leases, 2020	6,245
Operating leases, 2021	6,242
Operating leases, 2022	5,976
Operating leases, 2023	2,654
Operating leases, 2024 and thereafter	499
Total operating lease payments	26,411
Less imputed interest, Operating leases	4,156
Total operating lease liabilities	22,255
Finance Lease Liabilities, Payments, Due [Abstract]
Finance leases, Remainder of 2019	35
Finance leases, 2020	43
Finance leases, 2021	36
Total finance lease payments	114
Less imputed interest, Finance leases	6
Total finance lease liabilities	108
Lessee Lease Liability Payments Due [Abstract]
Remainder of 2019	4,830
2020	6,288
2021	6,278
2022	5,976
2023	2,654
2024 and thereafter	499
Total lease payments	26,525
Less imputed interest	4,162
Total lease liabilities	$ 22,363

Leases - Schedule of Future Minimum Lease Payments under Non-cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Lessee Disclosure [Abstract]
2020	$ 1,325
2021	1,134
2022	1,060
2023	947
2024 and thereafter	1,557
Total	$ 6,023

Leases (Details) $ in Millions	Dec. 31, 2018 USD ($)
Lessee Disclosure [Abstract]
Purchase obligation under manufacturing contract for 2019	$ 21.6
Purchase obligation under manufacturing contract for 2020	21.6
Purchase obligation under manufacturing contract for 2021	21.6
Purchase obligation under manufacturing contract for 2022	21.6
Purchase obligation under manufacturing contract for 2023	$ 21.6

Long-Term Debt and Revolving Loan (Details) - USD ($)			3 Months Ended
Long-Term Debt and Revolving Loan (Details) - USD ($)	Apr. 18, 2018	Jul. 25, 2017	Mar. 31, 2019	Mar. 31, 2018	Apr. 30, 2018	Apr. 17, 2018
Line Of Credit Facility [Line Items]
Credit and security agreement entered date		Jul. 25, 2017
Amortization of debt issuance costs			$ 100,000	$ 100,000
Additional interest (as a percent)		5.00%
Term Loan Credit Agreement
Line Of Credit Facility [Line Items]
Amount funded by MidCap under agreement		$ 25,000,000
Lines of credit facility available date	Apr. 30, 2018	Mar. 31, 2018
Loan amount outstanding		$ 40,000,000	35,000,000
Debt scheduled maturity date		Dec. 01, 2021
Origination fee (as a percent)		0.50%
Unamortized debt issuance costs on term loan, current portion			100,000
Unamortized debt issuance costs on term loan, long-term portion			$ 100,000
Term Loan Credit Agreement \| London Interbank Offered Rate (LIBOR)
Line Of Credit Facility [Line Items]
Spread on variable rate basis (as a percent)			7.50%
Debt Instrument Reference Rate			2.49%
Term Loan Credit Agreement \| Minimum \| London Interbank Offered Rate (LIBOR)
Line Of Credit Facility [Line Items]
Debt instrument, interest rate floor		1.00%
March Two Thousand Eighteen Term Loan
Line Of Credit Facility [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity		$ 10,000,000
Loan amount outstanding					$ 10,000,000	$ 10,000,000
Additional Term Loan
Line Of Credit Facility [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity		5,000,000
Minimum revenue required to satisfy additional term loan facility		75,000,000
Revolving Credit Agreement
Line Of Credit Facility [Line Items]
Loan amount outstanding		$ 10,000,000	$ 2,600,000
Borrowing base of accounts receivable (as a percent)		85.00%
Borrowing base of finished goods inventory (as a percent)		40.00%
Debt scheduled maturity date		Dec. 01, 2021
Origination fee (as a percent)		0.50%
Annual collateral management fee (as a percent)		0.50%
Annual unused line fee of average unused portion (as a percent)		0.50%
Revolving Credit Agreement \| Other Long-Term Assets
Line Of Credit Facility [Line Items]
Unamortized debt issuance costs on term loan, long-term portion			$ 100,000
Revolving Credit Agreement \| London Interbank Offered Rate (LIBOR)
Line Of Credit Facility [Line Items]
Spread on variable rate basis (as a percent)		4.50%
Revolving Credit Agreement \| Maximum
Line Of Credit Facility [Line Items]
Borrowing base availability from finished goods inventory (as a percent)		20.00%
Revolving Credit Agreement \| Minimum \| London Interbank Offered Rate (LIBOR)
Line Of Credit Facility [Line Items]
Debt instrument, interest rate floor		1.00%

Long-Term Debt and Revolving Loan (Schedule of Future Principal Payments for Outstanding Term Loans) (Details) - Term Loans $ in Thousands	Mar. 31, 2019 USD ($)
Line Of Credit Facility [Line Items]
Remainder of 2019	$ 7,000
2020	14,000
2021	14,000
Total	$ 35,000

Stockholders' Equity (Details) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Stock other disclosures
Common and preferred stock, shares authorized	210,000,000	210,000,000
Common stock, shares authorized	200,000,000	200,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Stockholders' Equity (Warrants) (Details) - $ / shares		1 Months Ended
Stockholders' Equity (Warrants) (Details) - $ / shares	Jan. 17, 2013	Jun. 30, 2014	Mar. 31, 2019
Common Stock Warrants
Aggregate number of common shares to purchase			47,710
Oxford Finance, LLC
Common Stock Warrants
Exercise price (in dollars per share)	$ 14.671	$ 14.671
Tranche A, B and C loans \| Oxford Finance, LLC
Common Stock Warrants
Warrant term	7 years
Percentage of term loan amounts	3.00%
Tranche D term loan \| Oxford Finance, LLC
Common Stock Warrants
Warrant term		7 years
Percentage of term loan amounts		2.50%

Stockholders' Equity (Options) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Nov. 03, 2014	Apr. 30, 2007
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grants	761,344
Stock options
Number of options
Balance at the beginning of period (in shares)	1,953,334
Options exercised (in shares)	(45,453)
Balance at the end of the period (in shares)	1,907,881		1,953,334
Weighted average exercise price
Balance at the beginning of period (in dollars per share)	$ 7.42
Options exercised (in dollars per share)	2.34
Balance at the end of period (in dollars per share)	$ 7.54		$ 7.42
Additional information
Weighted average remaining contractual term	6 years 2 months 15 days		6 years 3 months 18 days
Stock-based compensation expense	$ 0.2	$ 0.4
Unrecognized compensation costs (in dollars)	$ 0.4
Weighted average period over which unrecognized compensation costs are expected to be recognized	1 year
2007 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock initially reserved for issuance (in shares)					1,690,448
2014 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock initially reserved for issuance (in shares)				1,027,500
Number of shares available for future grants	1,346,169
Inducement Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grants	35,984
Number of shares awarded	1,019,211
Grant period of stock awards	10 years
Number of additional years of requisite service period	3 years
Vesting period	1 year
Inducement Plan \| On the first anniversary
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage	25.00%
Inducement Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase price of awards expressed as a percentage of fair value of shares on the date of grant	100.00%
Percentage of possible payouts of the target award	0.00%
Inducement Plan \| Minimum \| Individual options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage	25.00%
Inducement Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of possible payouts of the target award	100.00%
2007 Plan and 2014 Plan \| Stock options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant period of stock awards	10 years
2007 Plan and 2014 Plan \| Stock options \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase price of awards expressed as a percentage of fair value of shares on the date of grant	100.00%
Percentage of voting power owned by shareholder	10.00%
2007 Plan and 2014 Plan \| Stock options \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase price of awards expressed as a percentage of fair value of shares on the date of grant	110.00%

Stockholders' Equity (Restricted Stock) (Details) - Restricted stock units - 2014 Plan - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Stockholders' Equity, other disclosures
Requisite service period, annually	3 years
Stock-based compensation expense	$ 3.4	$ 2.0
Unrecognized compensation costs (in dollars)	$ 16.1
Weighted average period over which unrecognized compensation costs are expected to be recognized	2 years
Number of shares
Balance at beginning of the period	2,141,350
Granted	170,508
Vested	(671,245)
Forfeited	(102,206)
Balance at end of the period	1,538,407
Weighted average grant date fair value
Balance at beginning of the period	$ 13.27
Granted	11.37
Vested	10.96
Forfeited	19.48
Balance at end of the period	$ 13.65

Stockholders' Equity (Stock Purchase) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Oct. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grants	761,344
2014 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase period of offering	6 months
Rate of purchase price of stock on fair value (as a percent)	85.00%
Purchases under the award	68,899
Weighted Average purchase price	$ 9.91
Stock-based compensation expense	$ 0.2	$ 0.1
Incremental compensation cost	$ 0.4
2014 Employee Stock Purchase Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Discount rate on the value of shares through payroll deductions (as a percent)	15.00%
Expiration period of each offering	27 months
Number of shares reserved for future issuance			255,500

Income Taxes (Details) - USD ($)	3 Months Ended
Income Taxes (Details) - USD ($)	Mar. 31, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Tax expense	$ 0	$ 0

Segment Information (Details)	3 Months Ended
Segment Information (Details)	Mar. 31, 2019 USD ($) Segment
Segment Reporting [Abstract]
Number of reportable segments \| Segment	2
Segments unallocated expenses \| $	$ 0

Segment Information - Summary of Net Sales and Net Operating Loss by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total net sales	$ 17,552	$ 14,676
Total loss from operations	(25,851)	(18,927)
Total assets	171,625		$ 168,359
Breast Products
Segment Reporting Information [Line Items]
Total net sales	9,751	8,542
Total loss from operations	(14,032)	(12,794)
Total assets	126,385		130,149
miraDry
Segment Reporting Information [Line Items]
Total net sales	7,801	6,134
Total loss from operations	(11,819)	$ (6,133)
Total assets	$ 45,240		$ 38,210

Commitments and Contingencies (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Nov. 11, 2017	Mar. 31, 2019	Dec. 31, 2018
Contingencies
Loss contingency paid			$ 410
miraDry Class Action Litigation
Contingencies
Amount of Defendants (and/or their indemnitors and/or insurers) agreed to pay settlement consideration	$ 400
Legal settlement			600
Loss contingency paid			$ 400
Legal settlement paid		$ 400