Penumbra (PEN) 10-Q9 May 172017 Q1 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information Document - shares	3 Months Ended
Document and Entity Information Document - shares	Mar. 31, 2017	Apr. 14, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Penumbra Inc
Entity Central Index Key	1,321,732
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		33,627,160

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 109,383	$ 13,236
Marketable investments	122,256	115,517
Accounts receivable, net of doubtful accounts of $829 and $684 at March 31, 2017 and December 31, 2016, respectively	45,278	43,335
Inventories	79,187	73,012
Prepaid expenses and other current assets	14,554	18,727
Restricted cash	1,704
Total current assets	372,362	263,827
Property and equipment, net	22,905	21,464
Deferred taxes	22,486	22,476
Other non-current assets	612	487
Total assets	418,365	308,254
Current liabilities:
Accounts payable	4,973	4,110
Accrued liabilities	33,591	31,690
Total current liabilities	38,564	35,800
Deferred Rent Credit, Noncurrent	5,501	5,083
Other non-current liabilities	828	824
Total liabilities	44,893	41,707
Commitments and contingencies
Stockholders’ equity:
Common stock	33	31
Additional paid-in capital	383,132	273,865
Accumulated other comprehensive loss	(3,926)	(4,688)
Accumulated deficit	(5,767)	(2,661)
Total stockholders’ equity	373,472	266,547
Total liabilities and stockholders’ equity	$ 418,365	$ 308,254

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 829	$ 684	$ 589

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive (Loss) Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Revenue	$ 73,213	$ 57,919
Cost of revenue	25,504	18,014
Gross profit	47,709	39,905
Operating expenses:
Research and development	7,034	5,001
Sales, general and administrative	42,721	33,069
Total operating expenses	49,755	38,070
(Loss) Income from operations	(2,046)	1,835
Interest income, net	644	510
Other expense, net	(349)	(224)
(Loss) Income before provision for (benefit from) income taxes	(1,751)	2,121
Provision for (benefit from) income taxes	1,355	(170)
Net (loss) income	(3,106)	2,291
Foreign currency translation adjustments, net of tax	692	1,048
Unrealized gains on available-for-sale securities, net of tax	70	281
Comprehensive (loss) income	(2,344)	3,620
Net income attributable to common stockholders	$ (3,106)	$ 2,291
Net (loss) income per share attributable to common stockholders — Basic (in dollars per share)	$ (0.10)	$ 0.08
Net (loss) income per share attributable to common stockholders — Diluted (in dollars per share)	$ (0.10)	$ 0.07
Weighted average shares used to compute net (loss) income per share attributable to common stockholders — Basic (in shares)	31,611,841	29,990,006
Weighted average shares used to compute net (loss) income per share attributable to common stockholders — Diluted (in shares)	31,611,841	33,023,495

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net (loss) income	$ (3,106)	$ 2,291
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	654	538
Amortization of premium on marketable investments	299	189
Stock-based compensation	4,012	3,015
Provision for doubtful accounts	145	11
Inventory write downs	256	317
Loss on disposal of property and equipment	0	11
Realized (gain) loss on marketable investments	(31)	0
Deferred taxes	(1)	1,329
Changes in operating assets and liabilities:
Accounts receivable	(1,880)	(1,343)
Inventories	(6,057)	(9,083)
Prepaid expenses and other current and non-current assets	2,248	(4,759)
Accounts payable	889	1,350
Accrued expenses and other non-current liabilities	4,766	4,060
Net cash provided by (used in) operating activities	2,194	(2,074)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of marketable investments	(44,777)	(9,531)
Proceeds from sales of marketable investments	22,975	500
Proceeds from maturities of marketable investments	15,020	11,750
Purchases of property and equipment	(3,194)	(1,115)
Increase (Decrease) in Restricted Cash	(1,686)	0
Net cash (used in) provided by investing activities	(11,662)	1,604
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from Issuance of Common Stock	106,563	0
Proceeds from exercises of stock options	1,050	129
Payment of employee taxes related to vested restricted stock	(2,089)	(1,642)
Net cash provided by (used in) financing activities	105,524	(1,513)
Effect of foreign exchange rate changes on cash and cash equivalents	91	42
Net Increase (Decrease) In Cash And Cash Equivalents	96,147	(1,941)
CASH AND CASH EQUIVALENTS—Beginning of period	13,236	19,547
CASH AND CASH EQUIVALENTS—End of period	109,383	17,606
NONCASH INVESTING AND FINANCING ACTIVITIES:
Purchase of property and equipment funded through accounts payable and accrued liabilities	339	334
Deferred issuance costs not yet paid	$ 295	$ 0

Organization and Description of

Organization and Description of Business	3 Months Ended
Organization and Description of Business	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Penumbra, Inc. (the “Company”) is a global healthcare company focused on interventional therapies. The Company designs, develops, manufactures and markets innovative devices and has a broad portfolio of products that addresses challenging medical conditions and significant clinical needs across two major markets, neuro and peripheral vascular. The conditions that the Company’s products address include, among others, ischemic stroke, hemorrhagic stroke and various peripheral vascular conditions that can be treated through thrombectomy and embolization procedures.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation and Consolidation The accompanying condensed consolidated balance sheet as of March 31, 2017 , the condensed consolidated statements of operations and comprehensive (loss) income for the three months ended March 31, 2017 and 2016 , and the condensed consolidated statements of cash flows for the three months ended March 31, 2017 and 2016 are unaudited. The unaudited condensed consolidated financial statements included herein have been prepared by the Company in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and the applicable rules and regulations of the Securities and Exchange Commission (the “SEC”) for interim financial information. Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. The condensed consolidated balance sheet as of December 31, 2016 was derived from the audited financial statements as of that date. The unaudited condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all adjustments of a normal recurring nature considered necessary to state fairly the Company’s financial position as of March 31, 2017 , the results of its operations for the three months ended March 31, 2017 and 2016 , and the cash flows for the three months ended March 31, 2017 and 2016 . The results for the three months ended March 31, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017 or for any other future annual or interim period. Certain changes in presentation were made in the condensed consolidated financial statements for the three months ended March 31, 2016, to conform to the presentation for the three months ended March 31, 2017 . The Company elected to early adopt Accounting Standards Update ( “ ASU ” ) 2016-09 in the fourth quarter of 2016 which requires the Company to reflect any adjustments as of January 1, 2016, the beginning of the annual period that includes the interim period of adoption. The impact of adoption was the creation of deferred tax assets in the balance sheet and recognition of excess tax benefits in our provision for (benefit from) income taxes rather than paid-in capital for all periods in fiscal year 2016. The Company's adoption of ASU 2016-09 resulted in the recognition of excess tax benefits in the Company's benefit from income taxes rather than paid-in capital of $1.5 million for the three months ended March 31, 2016. In addition, the Company elected to apply the presentation requirements for cash flows related to excess tax benefits retrospectively to all periods presented. Adoption of the new standard resulted in adjustments to our 2016 unaudited selected financial data previously reported in our Quarterly Report on Form 10-Q as follows : March 31, 2016 (In thousands) As Reported As Adjusted Condensed Consolidated Balance Sheet Data: Additional Paid-in-Capital $ 255,499 $ 253,988 Accumulated deficit $ (16,695 ) $ (15,184 ) Total stockholder' equity $ 238,048 $ 238,048 Three Months Ended March 31, 2016 (In thousands, except percentage and per share amounts) As Reported As Adjusted Condensed Consolidated Statements of Operations Data: Provision for (benefit from) income taxes $ 1,341 $ (170 ) Net income $ 780 $ 2,291 Net income per share —Basic $ 0.03 $ 0.08 —Diluted $ 0.02 $ 0.07 Weighted average shares used to compute net income (loss) per share attributable to common stockholders —Basic 29,990,006 29,990,006 —Diluted 32,486,516 33,023,495 Three Months Ended March 31, 2016 (In thousands) As Reported As Adjusted Condensed Consolidated Statement of Cash Flow Data: Net cash (used in) operating activities $ (3,584 ) $ (2,074 ) Net cash (used in) financing activities $ (3 ) $ (1,513 ) The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2016 included in the Company ’ s Annual Report on Form 10-K. There have been no changes to the Company’s significant accounting policies during the three months ended March 31, 2017 , as compared to the significant accounting policies described in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016 . The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and equity accounts; disclosure of contingent assets and liabilities at the date of the financial statements; and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to marketable investments, provisions for doubtful accounts, sales return reserve, warranty reserves, valuation of inventories, useful lives of property and equipment, income taxes, and contingencies, among others. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other data. Actual results could differ from those estimates. Segments The Company determined its operating segment on the same basis that it uses to evaluate its performance internally. The Company has one business activity: the design, development, manufacturing and marketing of innovative medical devices, and operates as one operating segment. The Company’s chief operating decision-maker, its Chief Executive Officer, reviews its operating results for the purpose of allocating resources and evaluating financial performance. The Company determines revenue by geographic area, based on the destination to which it ships its products. Recent Accounting Guidance Recently Adopted Accounting Standards In July 2015, the Financial Accounting Standards Board ( “ FASB ”) issued ASU No. 2015-11, Simplifying the Measurement of Inventory , which requires an entity to measure most inventory at the lower of cost and net realizable value, thereby simplifying the current guidance under which an entity must measure inventory at the lower of cost or market. In January 2017, the Company adopted the standard on a prospective basis and the adoption did not have a material impact on its financial position. Recently Issued Accounting Standards In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers , which outlines a comprehensive new revenue recognition model designed to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In March 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers — Principal versus Agent Considerations (Reporting Revenue Gross versus Net) , which further clarifies the implementation guidance on principal versus agent considerations contained in ASU 2014-09. In April 2016, the FASB issued ASU 2016-10, Revenue from Contracts with Customers — Identifying Performance Obligations and Licensing , which further clarifies the implementation guidance relating to identifying performance obligations and the licensing implementation guidance. In May 2016, the FASB issued ASU 2016-12, Revenue from Contracts with Customers — Narrow-Scope improvements and Practical Expedients , which further clarifies the implementation on narrow scope improvements and practical expedients. In December 2016, the FASB issued ASU 2016-20, Technical Corrections and Improvements to Topic 606 — Revenue from Contracts with Customer s , which makes minor corrections or minor improvements to the Codification related to ASU No. 2014-09 that are not expected to have a significant effect on the Company ’ s current accounting practice. These standards will be effective for the Company in the first quarter of 2018 pursuant to ASU No. 2015-14, Revenue from Contracts with Customers - Deferral of the Effective Date , issued by the FASB in August 20 15. The Company is currently evaluating the financial statement impact of adopting these new standards as well as the transition method for implementation. The Company will be impacted by the new standard regarding the timing of its fulfillment of delivery criterion. In February 2016, the FASB issued ASU No. 2016-02, Leases , which amends the existing accounting standards for leases. Under the new guidance, a lessee will be required to recognize a lease liability and right-of-use asset for all leases with terms in excess of twelve months. The new guidance also modifies the classification criteria and accounting for sales-type and direct financing leases, and requires additional disclosures to enable users of financial statements to understand the amount, timing, and uncertainty of cash flows arising from leases. Consistent with current guidance, a lessee’s recognition, measurement, and presentation of expenses and cash flows arising from a lease will continue to depend primarily on its classification. The accounting standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and must be applied using a modified retrospective approach. Early adoption is permitted. While the Company is continuing to assess all potential impacts of the standard, it expects that most of its lease commitments will be subject to the updated standard and recognized as lease liabilities and right-of-use assets upon adoption. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses . The standard changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The Company will recognize an allowance for credit losses on available-for-sale securities rather than deductions in amortized cost. The standard is effective for fiscal years and interim periods beginning after December 15, 2019. Early adoption is permitted for all periods beginning after December 15, 2018. The Company is currently evaluating the impact of adopting this standard. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows: Restricted Cash , a consensus of the FASB Emerging Issues Task Force . The standard requires companies to include amounts generally described as restricted cash and restricted cash equivalents in cash and cash equivalents when reconciling the total beginning and end of period amounts shown on the statement of cash flows. The standard is effective for annual periods beginning after December 15, 2017, and interim periods within those annual periods. The Company does not expect the adoption of ASU 2016-18 to have a material impact on its consolidated financial statements.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
Fair Value of Financial Instruments	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. The accounting guidance establishes a three-tiered hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value: Level 1 - Quoted prices in active markets for identical assets or liabilities. Level 2 - Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based on the lowest level of input that is significant to the fair value measurement. The Company classifies its cash equivalents and marketable investments within Level 1 and Level 2, as it uses quoted market prices or alternative pricing sources and models utilizing market observable inputs. The Company determined the fair value of its Level 1 financial instruments, which are traded in active markets, using quoted market prices for identical instruments. Marketable investments classified within Level 2 of the fair value hierarchy are valued based on other observable inputs, including broker or dealer quotations or alternative pricing sources. When quoted prices in active markets for identical assets or liabilities are not available, the Company relies on non-binding quotes from its investment managers, which are based on proprietary valuation models of independent pricing services. These models generally use inputs such as observable market data, quoted market prices for similar instruments, historical pricing trends of a security relative to its peers. To validate the fair value determination provided by its investment managers, the Company reviews the pricing movement in the context of overall market trends and trading information from its investment managers. In addition, the Company assesses the inputs and methods used in determining the fair value in order to determine the classification of securities in the fair value hierarchy. The Company did not own any Level 3 financial assets or liabilities as of March 31, 2017 or December 31, 2016 . During the three months ended March 31, 2017 and 2016 , the Company did not record impairment charges related to its marketable investments, and the Company did not have any transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy. The Company did not have any financial assets and liabilities measured at fair value on a non-recurring basis as of March 31, 2017 or December 31, 2016 . The following table sets forth the Company’s financial assets and liabilities measured at fair value by level within the fair value hierarchy (in thousands): As of March 31, 2017 Level 1 Level 2 Level 3 Fair Value Financial Assets Cash equivalents: Commercial Paper $ — $ 21,769 $ — $ 21,769 Money market funds 55,608 — — 55,608 U.S. States and Municipalities — 5,000 — 5,000 Corporate bonds — 4,000 — 4,000 Marketable investments: Commercial paper — 13,610 — 13,610 U.S. Treasury 9,003 — 9,003 U.S. agency securities — 6,837 — 6,837 U.S. states and municipalities — 12,678 — 12,678 Corporate bonds — 78,926 — 78,926 Non-U.S. government debt securities — 1,202 — 1,202 Total $ 64,611 $ 144,022 $ — $ 208,633 As of December 31, 2016 Level 1 Level 2 Level 3 Fair Value Financial Assets Cash equivalents: Money market funds $ 873 $ — $ — $ 873 Marketable investments: Commercial paper — 4,238 — 4,238 U.S. Treasury 4,996 — — 4,996 U.S. agency securities — 8,794 — 8,794 U.S. states and municipalities — 27,355 — 27,355 Corporate bonds — 68,925 — 68,925 Non-U.S. government debt securities — 1,209 — 1,209 Total $ 5,869 $ 110,521 $ — $ 116,390

Balance Sheet Components

Balance Sheet Components	3 Months Ended
Balance Sheet Components	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	Balance Sheet Components Cash and Cash Equivalents The majority of the Company’s cash is held by one financial institution in the United States in an amount that exceeds federally insured limits. The Company maintained investments that were not federally insured in the form of money market funds during the periods presented. The Company also held cash in foreign banks of approximately $3.5 million and $2.1 million at March 31, 2017 and December 31, 2016 , respectively, which was not federally insured. The Company has not experienced any losses on its deposits of cash and cash equivalents. Restricted Cash The Company had restricted cash of $1.7 million at March 31, 2017 and no restricted cash at December 31, 2016 . The restricted cash is held in one of the Company’s foreign banks and has a temporary restriction pending final incorporation of an international subsidiary. The Company anticipates the restriction to be lifted before the end of the year. Accounts Receivable, Net The Company’s allowance for doubtful accounts comprised of the following (in thousands): Allowance for Doubtful Accounts March 31, December 31, Balance at the beginning of the period $ 684 $ 589 Charged to costs and expenses 145 216 Deductions — (121 ) Balance at the end of the period $ 829 $ 684 One customer (a distributor) accounted for 10% and 11% of the Company’s revenue during the three months ended March 31, 2017 and 2016 , respectively. No customer accounted for greater than 10% of the Company’s accounts receivable balance as of March 31, 2017 or December 31, 2016 . Prepaid Expenses and Other Current Assets The Company’s prepaid expenses and other current assets as of March 31, 2017 and December 31, 2016 were comprised of the following (in thousands): March 31, December 31, Prepaid Tax $ 1,887 $ 4,656 Prepaid expenses 4,871 4,573 Income tax receivable 4,587 4,536 Other current assets 3,209 4,962 Prepaid expenses and other current assets $ 14,554 $ 18,727 Marketable Investments The Company’s marketable investments as of March 31, 2017 and December 31, 2016 were as follows (in thousands): March 31, 2017 Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 13,610 $ 1 $ (1 ) $ 13,610 U.S. Treasury 9,002 4 (3 ) 9,003 U.S. agency securities 6,847 — (10 ) 6,837 U.S. states and municipalities 12,687 2 (11 ) 12,678 Corporate bonds 79,004 30 (108 ) 78,926 Non-U.S. government debt securities 1,202 — 1,202 Total $ 122,352 $ 37 $ (133 ) $ 122,256 December 31, 2016 Cost Gross Gross Fair Value Commercial paper $ 4,237 $ 1 $ — $ 4,238 U.S. Treasury 4,996 — — 4,996 U.S. agency securities 8,803 3 (12 ) 8,794 U.S. states and municipalities 27,429 1 (75 ) 27,355 Corporate bonds 69,009 36 (120 ) 68,925 Non-U.S. government debt securities 1,209 — — 1,209 Total $ 115,683 $ 41 $ (207 ) $ 115,517 The following tables present the gross unrealized losses and the fair value for those marketable investments that were in an unrealized loss position for less than twelve months as of March 31, 2017 and December 31, 2016 (in thousands): March 31, 2017 Fair Value Gross Unrealized Losses Commercial paper $ 7,977 $ (1 ) US Treasury 4,994 (3 ) US Agency securities 4,892 (10 ) U.S. States and Municipalities 9,947 (11 ) Corporate bonds 43,741 (108 ) Total $ 71,551 $ (133 ) December 31, 2016 Fair Value Gross Unrealized Losses U.S. agency securities $ 3,291 $ (12 ) U.S. states and municipalities 22,286 (75 ) Corporate bonds 29,748 (120 ) Total $ 55,325 $ (207 ) As of March 31, 2017 and December 31, 2016 , there were no securities that had been in a loss position for more than twelve months. The contractual maturities of the Company’s marketable investments as of March 31, 2017 and December 31, 2016 were as follows (in thousands): March 31, December 31, 2016 Fair Value Due in one year $ 105,348 $ 71,051 Due in one to five years 16,908 44,466 Total $ 122,256 $ 115,517 Inventories Inventories are stated at the lower of cost (determined under the first-in first-out method) or market. Inventory quantities are reviewed in consideration of actual loss experience, projected future demand and remaining shelf life to record a provision for excess and obsolete inventory when appropriate. The components of inventories as of March 31, 2017 and December 31, 2016 consisted of the following (in thousands): March 31, December 31, Raw materials $ 9,910 $ 11,367 Work in process 4,420 3,663 Finished goods 64,857 57,982 Inventories $ 79,187 $ 73,012 Property and Equipment, Net Property and equipment, net as of March 31, 2017 and December 31, 2016 consisted of the following (in thousands): March 31, December 31, Machinery and equipment $ 10,457 $ 9,734 Furniture and fixtures 4,598 4,246 Leasehold improvements 10,291 10,207 Software 1,641 1,221 Computers 1,118 884 Construction in progress 2,453 2,193 Total property and equipment 30,558 28,485 Less: Accumulated depreciation and amortization (7,653 ) (7,021 ) Property and equipment, net $ 22,905 $ 21,464 Depreciation and amortization expense was $0.7 million and $0.5 million for the three months ended March 31, 2017 and 2016 , respectively . Accrued Liabilities The following table shows the components of accrued liabilities as of March 31, 2017 and December 31, 2016 (in thousands): March 31, December 31, Payroll and employee-related cost $ 19,223 $ 16,956 Sales return reserve 2,940 2,753 Preclinical and clinical trial cost 1,877 2,054 Deferred revenue 357 344 Product warranty 1,087 1,254 Sales tax and VAT payable 548 733 Income tax payable 354 174 Other accrued liabilities 7,205 7,422 Total accrued liabilities $ 33,591 $ 31,690 The estimated product warranty accrual as of March 31, 2017 and December 31, 2016 was as follows (in thousands): March 31, December 31, Balance at the beginning of the period $ 1,254 $ 713 Accruals of warranties issued 39 1,176 Settlements of warranty claims (206 ) (635 ) Balance at the end of the period $ 1,087 $ 1,254

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Commitments The Company leases its offices under non-cancelable operating leases that expire at various dates from 2029 to 2031. Rent expense for non-cancelable operating leases with scheduled rent increases is recognized on a straight-line basis over the lease term. Rent expense for the three months ended March 31, 2017 and 2016 was $1.4 million and $1.1 million , respectively. In addition, the Company's lease commitments also require it to make additional payments during the lease term for taxes, insurance and other operating expenses. The Company leases its other equipment under non-cancelable operating leases that expire at various dates through 2021 . Royalty Obligations In March 2005, the Company entered into a license agreement that requires the Company to make minimum royalty payments to the licensor on a quarterly basis. As of both March 31, 2017 and December 31, 2016 , the license agreement required minimum annual royalty payments of $0.1 million in equal quarterly installments. On each January 1, the quarterly calendar year minimum royalty will be adjusted to equal the prior year’s minimum royalty adjusted by a percentage equal to the percentage change in the “consumer price index for all urban consumers” for the prior calendar year as reported by the U.S. Department of Labor. Unless terminated earlier, the term of the license agreement will continue until the expiration of the last to expire patent that covers that licensed product or 2022, whichever is longer. In April 2012, the Company entered into an agreement that requires the Company to pay, on a quarterly basis, a 5% royalty on sales of products covered under applicable patents. Unless the agreement is terminated earlier, the royalty term for each applicable product will continue until the expirations of the applicable patent covering such product or 2029, whichever is longer. In November 2013, the Company entered into an agreement that requires the Company to pay, on a quarterly basis, a 3% royalty on the first $5 million in sales and a 1% royalty on sales thereafter of products covered under applicable patents. Unless the agreement is terminated earlier, the royalty for each covered product shall continue until 2030. In April 2015, the Company entered into a royalty agreement that requires the Company to pay, on a quarterly basis, a 2% royalty on sales of certain products covered by the agreement. Unless the royalty agreement is terminated earlier, the royalty term for each covered product shall continue until 2035. Royalty expense included in cost of sales for the three months ended March 31, 2017 and 2016 was $0.8 million and $0.7 million , respectively. Contingencies From time to time, the Company may have certain contingent liabilities that arise 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. Indemnification The Company enters into standard indemnification arrangements in the ordinary course of business. In many such arrangements, the Company agrees to indemnify, hold harmless, and reimburse the indemnified parties for losses suffered or incurred by the indemnified parties in connection with any trade secret, copyright, patent or other intellectual property infringement claim by any third-party with respect to the Company’s technology. The Company also agrees to indemnify many purchasers for product defect and similar claims. The term of these indemnification agreements is generally perpetual. The maximum potential amount of future payments the Company could be required to make under these agreements is not determinable because it involves claims that may be made against the Company in the future, but have not yet been made. The Company has entered into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers, other than liabilities arising from willful misconduct of the individual. The Company has not incurred costs to defend lawsuits or settle claims related to these indemnification agreements. No liability associated with any of these indemnification requirements has been recorded to date. Litigation The Company was contacted in 2015 by the attorney for a potential product liability claimant who allegedly suffered injuries as a result of an aneurysm procedure in which the Penumbra Coil 400 was used. On February 19, 2016, a complaint for damages was filed on behalf of this claimant against Penumbra and the hospital involved in the procedure ( Montgomery v. Penumbra, Inc., et al., Case No. 16-2-04050-1 SEA, Superior Court of the State of Washington, King County) . The suit alleges liability primarily under the Washington Product Liability Act and seeks both compensatory and punitive damages without a specific damages claim. Counsel for the claimant previously indicated that he expects that a jury could award $35 million in damages were this matter to go to trial. This amount is substantially in excess of the Company’s insurance coverage. The hospital defendant had requested indemnification from the Company but was dismissed from the case in July 2016. The case is in the discovery phase, and the Company is unable to assess the merits of the plaintiff’s case. The Company intends to vigorously defend the litigation, as the Company believes there will be substantial questions regarding causation, liability and damages. From time to time, the Company is subject to claims and assessments in the ordinary course of business. The Company is not currently a party to any litigation matter that, individually or in the aggregate, is expected to have a material adverse effect on the Company’s business, financial condition, results of operations or cash flows.

Stockholder's Equity

Stockholder's Equity	3 Months Ended
Stockholder's Equity	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stockholder's Equity	Stockholder's Equity Common Stock In March 2017, the Company issued and sold an aggregate of 1,495,000 shares of common stock at a public offering price of $76.00 per share, less the underwriters ’ discounts and commissions, pursuant to an underwritten public offering . The Company received approximately $106.3 million in net cash proceeds after deducting underwriting discounts and commissions of $6.8 million and other offering expenses of $0.5 million . Equity Incentive Plans Stock Options Activity of stock options under the Penumbra, Inc. 2005 Stock Plan, the Penumbra, Inc. 2011 Equity Incentive Plan and the Amended and Restated Penumbra, Inc. 2014 Equity Incentive Plan (collectively the “Plans”) during the three months ended March 31, 2017 is set forth below: Number of Shares Weighted- Average Exercise Price Balance at December 31, 2016 2,876,955 $ 14.63 Options exercised (383,457 ) 2.73 Options canceled (969 ) 10.56 Balance at March 31, 2017 2,492,529 16.47 Restricted Stock and Restricted Stock Units The following table summarizes the activity of unvested restricted stock and restricted stock units under the Plans during the three months ended March 31, 2017 is set forth below: Number of Shares Weighted Average Grant Date Fair Value Unvested at December 31, 2016 1,002,944 $ 29.44 Granted 58,660 76.47 Vested (115,685 ) 15.63 Canceled/Forfeited (18,125 ) 41.31 Unvested and expected to vest at March 31, 2017 927,794 25.84 Stock-based Compensation The following table sets forth the stock-based compensation expense included in the Company's condensed consolidated statements of operations and comprehensive (loss) income for the three months ended March 31, 2017 and 2016 (in thousands): Three Months Ended March 31, 2017 2016 Cost of sales $ 309 $ 9 Research and development 253 258 Sales, general and administrative 3,450 2,748 Total $ 4,012 $ 3,015 As of March 31, 2017 , total unrecognized compensation cost was $34.6 million related to unvested share-based compensation arrangements which is expected to be recognized over a weighted average period of 2.7 years. The total stock-based compensation cost capitalized in inventory was $0.4 million and $0.4 million as of March 31, 2017 and December 31, 2016 , respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive (Loss) Income	3 Months Ended
Accumulated Other Comprehensive (Loss) Income	Mar. 31, 2017
Equity [Abstract]
Accumulated Other Comprehensive (Loss) Income	Accumulated Other Comprehensive (Loss) Income Other comprehensive income consists of two components: unrealized gains or losses on the Company’s available-for-sale marketable investments, and gains or losses from foreign currency translation adjustments. Until realized and reported as a component of net income, these comprehensive income items accumulate and are included within accumulated other comprehensive (loss) income. Unrealized gains and losses on the Company’s marketable investments are reclassified from accumulated other comprehensive (loss) income into earnings when realized upon sale, and are determined based on specific identification of securities sold. Gains and losses from the translation of assets and liabilities denominated in non-U.S. dollar functional currencies are included in accumulated other comprehensive (loss) income. The following table summarizes the changes in the accumulated balances during the three months ended March 31, 2017 and 2016 , and includes information regarding the manner in which the reclassifications out of accumulated other comprehensive (loss) income into earnings affect the Company’s condensed consolidated statements of operations and comprehensive (loss) income (in thousands): Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Marketable Currency Translation Total Marketable Currency Translation Total Balance at beginning of the period $ (105 ) $ (4,583 ) $ (4,688 ) $ (163 ) $ (1,952 ) $ (2,115 ) Other comprehensive income before reclassifications: Unrealized gains —marketable investments 101 — 101 441 — 441 Foreign currency translation gains — 692 692 — 1,043 1,043 Income tax effect—benefit (expense) — — — (160 ) 5 (155 ) Net of tax 101 692 793 281 1,048 1,329 Amounts reclassified from accumulated other comprehensive income to earnings: Realized losses (gains)—marketable investments (31 ) — (31 ) — — — Income tax effect—(expense) benefit — — — — — — Net of tax (31 ) — (31 ) — — — Net current-year other comprehensive income 70 692 762 281 1,048 1,329 Balance at end of the period $ (35 ) $ (3,891 ) $ (3,926 ) $ 118 $ (904 ) $ (786 )

Income Taxes

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company’s income tax expense, deferred tax assets and liabilities, and reserves for unrecognized tax benefits reflect management’s best assessment of estimated current and future taxes to be paid. The Company is subject to income taxes in both the United States and foreign jurisdictions. Significant judgment and estimates are required in determining the consolidated income tax expense. During interim periods, the Company generally utilizes the estimated annual effective tax rate method which involves the use of forecasted information. Under this method, the provision is calculated by applying an estimate of the annual effective tax rate for the full fiscal year to “ordinary” income or loss (pretax income or loss excluding unusual or infrequently occurring discrete items) for the reporting period. The Company’s effective tax rate decreased to ( 77.4% ) for the three months ended March 31, 2017 , compared to ( 8.0% ) for the three months ended March 31, 2016 , which includes the retroactive adoption of ASU 2016-09. The decrease in rate was primarily attributable to recording a partial valuation allowance against the deferred tax assets (“DTAs”) as of March 31, 2017 and the year-to-date tax impact from recognizing the deferred tax assets associated with intra-entity asset transfers. As of March 31, 2017 , the Company determined there were significant DTAs that needed to be assessed if the DTAs were more likely than not to be realized. Significant DTAs were created in the year ended December 31, 2016 and three month ended March 31, 2017 , driven by stock option exercises and vesting of restricted stock and the excess tax benefits resulting from the application of ASU 2016-09. The Company assessed its ability to realize the net DTAs by evaluating all available positive and negative evidence, including (1) cumulative results of operations in recent years, (2) sources of recent pre-tax losses, (3) estimates of future taxable income, and (4) the length of NOLs carryforward periods. The Company would be in a 3 -year cumulative taxable income position, had it not been for the impact of a $74.9 million excess tax deduction of stock based compensation under ASU 2016-09. Additionally, the Company considered the length of NOL carryforward periods and an objectively verifiable estimate of future income based on operating results from the Company’s recent history, as well as an estimate of future income that incorporates the Company's forecasted operating results for fiscal 2017. The Company believes that the recent period operating losses are attributable to operating expenses incurred to invest in the future growth of the business. Due to the significant amount of additional stock based compensation excess tax deduction generated, the Company determined that the negative evidence outweighed the positive evidence and that it is not more-likely-than-not that sufficient taxable income will be generated to realize all of the DTAs as of March 31, 2017. As such, a partial valuation allowance was recorded against the Company’s domestic DTAs as of March 31, 2017 in the amount of $9.8 million , which was approximately the same amount as the stock based compensation excess tax benefits created during the three months ended March 31, 2017 . The Company will continue to closely monitor the need for an additional valuation allowance against its domestic DTAs that are generated in each subsequent reporting period which can be impacted by actual operating results compared to the Company's forecast. Consistent with prior periods, the Company maintained a full valuation allowance against its California and Canada DTAs as of March 31, 2017 .

Net (Loss) Income per Share of

Net (Loss) Income per Share of Common Stock attributable to Common Stockholders	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Net (loss) Income per Share of Common Stock attributable to Common Stockholders	Net (Loss) Income per Share The Company’s basic net income per share is calculated by dividing the net income by the weighted average number of shares of common stock outstanding for the period. The diluted net (loss) income per share is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. For purposes of this calculation, options to purchase common stock, restricted stock and common stock warrants are considered common stock equivalents. A reconciliation of the numerator and denominator used in the calculation of the basic and diluted net (loss) income per share for the three months ended March 31, 2017 and 2016 is as follows (in thousands, except share and per share amounts): Three Months Ended March 31, 2017 2016 Net (loss) income per share: Numerator Net (loss) income—basic and diluted $ (3,106 ) $ 2,291 Denominator Weighted average shares used to compute net (loss) income —Basic 31,611,841 29,990,006 Potential dilutive stock-based awards, as calculated using treasury stock method — 3,033,489 Weighted average shares used to compute net income —Diluted 31,611,841 33,023,495 Net (loss) income per share —Basic $ (0.10 ) $ 0.08 —Diluted $ (0.10 ) $ 0.07 For the three months ended March 31, 2017 and 2016 , outstanding stock-based awards of 3.5 million and 12,500 shares, respectively, were excluded from the computation of diluted net income per share because their effect would have been anti-dilutive.

Geographic Areas and Product Sa

Geographic Areas and Product Sales	3 Months Ended
Geographic Areas and Product Sales	Mar. 31, 2017
Segment Reporting [Abstract]
Geographic Areas and Product Sales	Geographic Areas and Product Sales The Company’s revenue by geographic area, based on the destination to which the Company ships its products, for the three months ended March 31, 2017 and 2016 was as follows (in thousands): Three Months Ended March 31, 2017 2016 United States $ 48,487 $ 39,412 Japan 7,642 6,161 Other International 17,084 12,346 Total $ 73,213 $ 57,919 The following table sets forth revenue by product category, for the three months ended March 31, 2017 and 2016 was as follows (in thousands): Three Months Ended March 31, 2017 2016 Neuro $ 50,249 $ 41,284 Peripheral Vascular 22,964 16,635 Total $ 73,213 $ 57,919 The Company does not have significant long-lived assets outside the United States.

Summary of Significant Accoun16

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying condensed consolidated balance sheet as of March 31, 2017 , the condensed consolidated statements of operations and comprehensive (loss) income for the three months ended March 31, 2017 and 2016 , and the condensed consolidated statements of cash flows for the three months ended March 31, 2017 and 2016 are unaudited. The unaudited condensed consolidated financial statements included herein have been prepared by the Company in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and the applicable rules and regulations of the Securities and Exchange Commission (the “SEC”) for interim financial information. Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. The condensed consolidated balance sheet as of December 31, 2016 was derived from the audited financial statements as of that date. The unaudited condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all adjustments of a normal recurring nature considered necessary to state fairly the Company’s financial position as of March 31, 2017 , the results of its operations for the three months ended March 31, 2017 and 2016 , and the cash flows for the three months ended March 31, 2017 and 2016 . The results for the three months ended March 31, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017 or for any other future annual or interim period. Certain changes in presentation were made in the condensed consolidated financial statements for the three months ended March 31, 2016, to conform to the presentation for the three months ended March 31, 2017 . The Company elected to early adopt Accounting Standards Update ( “ ASU ” ) 2016-09 in the fourth quarter of 2016 which requires the Company to reflect any adjustments as of January 1, 2016, the beginning of the annual period that includes the interim period of adoption. The impact of adoption was the creation of deferred tax assets in the balance sheet and recognition of excess tax benefits in our provision for (benefit from) income taxes rather than paid-in capital for all periods in fiscal year 2016. The Company's adoption of ASU 2016-09 resulted in the recognition of excess tax benefits in the Company's benefit from income taxes rather than paid-in capital of $1.5 million for the three months ended March 31, 2016. In addition, the Company elected to apply the presentation requirements for cash flows related to excess tax benefits retrospectively to all periods presented. Adoption of the new standard resulted in adjustments to our 2016 unaudited selected financial data previously reported in our Quarterly Report on Form 10-Q as follows : March 31, 2016 (In thousands) As Reported As Adjusted Condensed Consolidated Balance Sheet Data: Additional Paid-in-Capital $ 255,499 $ 253,988 Accumulated deficit $ (16,695 ) $ (15,184 ) Total stockholder' equity $ 238,048 $ 238,048 Three Months Ended March 31, 2016 (In thousands, except percentage and per share amounts) As Reported As Adjusted Condensed Consolidated Statements of Operations Data: Provision for (benefit from) income taxes $ 1,341 $ (170 ) Net income $ 780 $ 2,291 Net income per share —Basic $ 0.03 $ 0.08 —Diluted $ 0.02 $ 0.07 Weighted average shares used to compute net income (loss) per share attributable to common stockholders —Basic 29,990,006 29,990,006 —Diluted 32,486,516 33,023,495 Three Months Ended March 31, 2016 (In thousands) As Reported As Adjusted Condensed Consolidated Statement of Cash Flow Data: Net cash (used in) operating activities $ (3,584 ) $ (2,074 ) Net cash (used in) financing activities $ (3 ) $ (1,513 ) The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2016 included in the Company ’ s Annual Report on Form 10-K. There have been no changes to the Company’s significant accounting policies during the three months ended March 31, 2017 , as compared to the significant accounting policies described in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016 . The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and equity accounts; disclosure of contingent assets and liabilities at the date of the financial statements; and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to marketable investments, provisions for doubtful accounts, sales return reserve, warranty reserves, valuation of inventories, useful lives of property and equipment, income taxes, and contingencies, among others. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other data. Actual results could differ from those estimates.
Segments	Segments The Company determined its operating segment on the same basis that it uses to evaluate its performance internally. The Company has one business activity: the design, development, manufacturing and marketing of innovative medical devices, and operates as one operating segment. The Company’s chief operating decision-maker, its Chief Executive Officer, reviews its operating results for the purpose of allocating resources and evaluating financial performance. The Company determines revenue by geographic area, based on the destination to which it ships its products.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers , which outlines a comprehensive new revenue recognition model designed to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In March 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers — Principal versus Agent Considerations (Reporting Revenue Gross versus Net) , which further clarifies the implementation guidance on principal versus agent considerations contained in ASU 2014-09. In April 2016, the FASB issued ASU 2016-10, Revenue from Contracts with Customers — Identifying Performance Obligations and Licensing , which further clarifies the implementation guidance relating to identifying performance obligations and the licensing implementation guidance. In May 2016, the FASB issued ASU 2016-12, Revenue from Contracts with Customers — Narrow-Scope improvements and Practical Expedients , which further clarifies the implementation on narrow scope improvements and practical expedients. In December 2016, the FASB issued ASU 2016-20, Technical Corrections and Improvements to Topic 606 — Revenue from Contracts with Customer s , which makes minor corrections or minor improvements to the Codification related to ASU No. 2014-09 that are not expected to have a significant effect on the Company ’ s current accounting practice. These standards will be effective for the Company in the first quarter of 2018 pursuant to ASU No. 2015-14, Revenue from Contracts with Customers - Deferral of the Effective Date , issued by the FASB in August 20 15. The Company is currently evaluating the financial statement impact of adopting these new standards as well as the transition method for implementation. The Company will be impacted by the new standard regarding the timing of its fulfillment of delivery criterion. In February 2016, the FASB issued ASU No. 2016-02, Leases , which amends the existing accounting standards for leases. Under the new guidance, a lessee will be required to recognize a lease liability and right-of-use asset for all leases with terms in excess of twelve months. The new guidance also modifies the classification criteria and accounting for sales-type and direct financing leases, and requires additional disclosures to enable users of financial statements to understand the amount, timing, and uncertainty of cash flows arising from leases. Consistent with current guidance, a lessee’s recognition, measurement, and presentation of expenses and cash flows arising from a lease will continue to depend primarily on its classification. The accounting standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and must be applied using a modified retrospective approach. Early adoption is permitted. While the Company is continuing to assess all potential impacts of the standard, it expects that most of its lease commitments will be subject to the updated standard and recognized as lease liabilities and right-of-use assets upon adoption. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses . The standard changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The Company will recognize an allowance for credit losses on available-for-sale securities rather than deductions in amortized cost. The standard is effective for fiscal years and interim periods beginning after December 15, 2019. Early adoption is permitted for all periods beginning after December 15, 2018. The Company is currently evaluating the impact of adopting this standard. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows: Restricted Cash , a consensus of the FASB Emerging Issues Task Force . The standard requires companies to include amounts generally described as restricted cash and restricted cash equivalents in cash and cash equivalents when reconciling the total beginning and end of period amounts shown on the statement of cash flows. The standard is effective for annual periods beginning after December 15, 2017, and interim periods within those annual periods. The Company does not expect the adoption of ASU 2016-18 to have a material impact on its consolidated financial statements.

Summary of Significant Accoun17

Summary of Significant Accounting Policies (Tables)	3 Months Ended
Summary of Significant Accounting Policies (Tables)	Mar. 31, 2017
Accounting Policies [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	Adoption of the new standard resulted in adjustments to our 2016 unaudited selected financial data previously reported in our Quarterly Report on Form 10-Q as follows : March 31, 2016 (In thousands) As Reported As Adjusted Condensed Consolidated Balance Sheet Data: Additional Paid-in-Capital $ 255,499 $ 253,988 Accumulated deficit $ (16,695 ) $ (15,184 ) Total stockholder' equity $ 238,048 $ 238,048 Three Months Ended March 31, 2016 (In thousands, except percentage and per share amounts) As Reported As Adjusted Condensed Consolidated Statements of Operations Data: Provision for (benefit from) income taxes $ 1,341 $ (170 ) Net income $ 780 $ 2,291 Net income per share —Basic $ 0.03 $ 0.08 —Diluted $ 0.02 $ 0.07 Weighted average shares used to compute net income (loss) per share attributable to common stockholders —Basic 29,990,006 29,990,006 —Diluted 32,486,516 33,023,495 Three Months Ended March 31, 2016 (In thousands) As Reported As Adjusted Condensed Consolidated Statement of Cash Flow Data: Net cash (used in) operating activities $ (3,584 ) $ (2,074 ) Net cash (used in) financing activities $ (3 ) $ (1,513 )

Fair Value of Financial Instr18

Fair Value of Financial Instruments (Tables)	3 Months Ended
Fair Value of Financial Instruments (Tables)	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Assets and Liabilities	The following table sets forth the Company’s financial assets and liabilities measured at fair value by level within the fair value hierarchy (in thousands): As of March 31, 2017 Level 1 Level 2 Level 3 Fair Value Financial Assets Cash equivalents: Commercial Paper $ — $ 21,769 $ — $ 21,769 Money market funds 55,608 — — 55,608 U.S. States and Municipalities — 5,000 — 5,000 Corporate bonds — 4,000 — 4,000 Marketable investments: Commercial paper — 13,610 — 13,610 U.S. Treasury 9,003 — 9,003 U.S. agency securities — 6,837 — 6,837 U.S. states and municipalities — 12,678 — 12,678 Corporate bonds — 78,926 — 78,926 Non-U.S. government debt securities — 1,202 — 1,202 Total $ 64,611 $ 144,022 $ — $ 208,633 As of December 31, 2016 Level 1 Level 2 Level 3 Fair Value Financial Assets Cash equivalents: Money market funds $ 873 $ — $ — $ 873 Marketable investments: Commercial paper — 4,238 — 4,238 U.S. Treasury 4,996 — — 4,996 U.S. agency securities — 8,794 — 8,794 U.S. states and municipalities — 27,355 — 27,355 Corporate bonds — 68,925 — 68,925 Non-U.S. government debt securities — 1,209 — 1,209 Total $ 5,869 $ 110,521 $ — $ 116,390

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
Balance Sheet Components (Tables)	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Allowance for Doubtful Accounts	The Company’s allowance for doubtful accounts comprised of the following (in thousands): Allowance for Doubtful Accounts March 31, December 31, Balance at the beginning of the period $ 684 $ 589 Charged to costs and expenses 145 216 Deductions — (121 ) Balance at the end of the period $ 829 $ 684
Schedule of Prepaid Expenses and Other Current Assets	The Company’s prepaid expenses and other current assets as of March 31, 2017 and December 31, 2016 were comprised of the following (in thousands): March 31, December 31, Prepaid Tax $ 1,887 $ 4,656 Prepaid expenses 4,871 4,573 Income tax receivable 4,587 4,536 Other current assets 3,209 4,962 Prepaid expenses and other current assets $ 14,554 $ 18,727
Schedule of Marketable Investments	The Company’s marketable investments as of March 31, 2017 and December 31, 2016 were as follows (in thousands): March 31, 2017 Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 13,610 $ 1 $ (1 ) $ 13,610 U.S. Treasury 9,002 4 (3 ) 9,003 U.S. agency securities 6,847 — (10 ) 6,837 U.S. states and municipalities 12,687 2 (11 ) 12,678 Corporate bonds 79,004 30 (108 ) 78,926 Non-U.S. government debt securities 1,202 — 1,202 Total $ 122,352 $ 37 $ (133 ) $ 122,256 December 31, 2016 Cost Gross Gross Fair Value Commercial paper $ 4,237 $ 1 $ — $ 4,238 U.S. Treasury 4,996 — — 4,996 U.S. agency securities 8,803 3 (12 ) 8,794 U.S. states and municipalities 27,429 1 (75 ) 27,355 Corporate bonds 69,009 36 (120 ) 68,925 Non-U.S. government debt securities 1,209 — — 1,209 Total $ 115,683 $ 41 $ (207 ) $ 115,517
Schedule of the Fair Value of Marketable Investments in an Unrealized Loss Position for Less than Twelve Months	The following tables present the gross unrealized losses and the fair value for those marketable investments that were in an unrealized loss position for less than twelve months as of March 31, 2017 and December 31, 2016 (in thousands): March 31, 2017 Fair Value Gross Unrealized Losses Commercial paper $ 7,977 $ (1 ) US Treasury 4,994 (3 ) US Agency securities 4,892 (10 ) U.S. States and Municipalities 9,947 (11 ) Corporate bonds 43,741 (108 ) Total $ 71,551 $ (133 ) December 31, 2016 Fair Value Gross Unrealized Losses U.S. agency securities $ 3,291 $ (12 ) U.S. states and municipalities 22,286 (75 ) Corporate bonds 29,748 (120 ) Total $ 55,325 $ (207 )
Schedule of Contractual Maturities of Marketable Investments	The contractual maturities of the Company’s marketable investments as of March 31, 2017 and December 31, 2016 were as follows (in thousands): March 31, December 31, 2016 Fair Value Due in one year $ 105,348 $ 71,051 Due in one to five years 16,908 44,466 Total $ 122,256 $ 115,517
Schedule of Inventories	The components of inventories as of March 31, 2017 and December 31, 2016 consisted of the following (in thousands): March 31, December 31, Raw materials $ 9,910 $ 11,367 Work in process 4,420 3,663 Finished goods 64,857 57,982 Inventories $ 79,187 $ 73,012
Schedule of Property and Equipment, Net	Property and equipment, net as of March 31, 2017 and December 31, 2016 consisted of the following (in thousands): March 31, December 31, Machinery and equipment $ 10,457 $ 9,734 Furniture and fixtures 4,598 4,246 Leasehold improvements 10,291 10,207 Software 1,641 1,221 Computers 1,118 884 Construction in progress 2,453 2,193 Total property and equipment 30,558 28,485 Less: Accumulated depreciation and amortization (7,653 ) (7,021 ) Property and equipment, net $ 22,905 $ 21,464
Schedule of Accrued Liabilities	The following table shows the components of accrued liabilities as of March 31, 2017 and December 31, 2016 (in thousands): March 31, December 31, Payroll and employee-related cost $ 19,223 $ 16,956 Sales return reserve 2,940 2,753 Preclinical and clinical trial cost 1,877 2,054 Deferred revenue 357 344 Product warranty 1,087 1,254 Sales tax and VAT payable 548 733 Income tax payable 354 174 Other accrued liabilities 7,205 7,422 Total accrued liabilities $ 33,591 $ 31,690
Schedule of Estimated Product Warranty Accrual	The estimated product warranty accrual as of March 31, 2017 and December 31, 2016 was as follows (in thousands): March 31, December 31, Balance at the beginning of the period $ 1,254 $ 713 Accruals of warranties issued 39 1,176 Settlements of warranty claims (206 ) (635 ) Balance at the end of the period $ 1,087 $ 1,254

Stockholder's Equity (Tables)

Stockholder's Equity (Tables)	3 Months Ended
Stockholder's Equity (Tables)	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock Option Activity	Activity of stock options under the Penumbra, Inc. 2005 Stock Plan, the Penumbra, Inc. 2011 Equity Incentive Plan and the Amended and Restated Penumbra, Inc. 2014 Equity Incentive Plan (collectively the “Plans”) during the three months ended March 31, 2017 is set forth below: Number of Shares Weighted- Average Exercise Price Balance at December 31, 2016 2,876,955 $ 14.63 Options exercised (383,457 ) 2.73 Options canceled (969 ) 10.56 Balance at March 31, 2017 2,492,529 16.47
Summary of Unvested Restricted Stock and Restricted Stock Unit Activity	The following table summarizes the activity of unvested restricted stock and restricted stock units under the Plans during the three months ended March 31, 2017 is set forth below: Number of Shares Weighted Average Grant Date Fair Value Unvested at December 31, 2016 1,002,944 $ 29.44 Granted 58,660 76.47 Vested (115,685 ) 15.63 Canceled/Forfeited (18,125 ) 41.31 Unvested and expected to vest at March 31, 2017 927,794 25.84
Schedule of Stock-based Compensation Expense	The following table sets forth the stock-based compensation expense included in the Company's condensed consolidated statements of operations and comprehensive (loss) income for the three months ended March 31, 2017 and 2016 (in thousands): Three Months Ended March 31, 2017 2016 Cost of sales $ 309 $ 9 Research and development 253 258 Sales, general and administrative 3,450 2,748 Total $ 4,012 $ 3,015

Accumulated Other Comprehensi21

Accumulated Other Comprehensive (Loss) Income (Tables)	3 Months Ended
Accumulated Other Comprehensive (Loss) Income (Tables)	Mar. 31, 2017
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table summarizes the changes in the accumulated balances during the three months ended March 31, 2017 and 2016 , and includes information regarding the manner in which the reclassifications out of accumulated other comprehensive (loss) income into earnings affect the Company’s condensed consolidated statements of operations and comprehensive (loss) income (in thousands): Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Marketable Currency Translation Total Marketable Currency Translation Total Balance at beginning of the period $ (105 ) $ (4,583 ) $ (4,688 ) $ (163 ) $ (1,952 ) $ (2,115 ) Other comprehensive income before reclassifications: Unrealized gains —marketable investments 101 — 101 441 — 441 Foreign currency translation gains — 692 692 — 1,043 1,043 Income tax effect—benefit (expense) — — — (160 ) 5 (155 ) Net of tax 101 692 793 281 1,048 1,329 Amounts reclassified from accumulated other comprehensive income to earnings: Realized losses (gains)—marketable investments (31 ) — (31 ) — — — Income tax effect—(expense) benefit — — — — — — Net of tax (31 ) — (31 ) — — — Net current-year other comprehensive income 70 692 762 281 1,048 1,329 Balance at end of the period $ (35 ) $ (3,891 ) $ (3,926 ) $ 118 $ (904 ) $ (786 )

Net (Loss) Income per Share o22

Net (Loss) Income per Share of Common Stock attributable to Common Stockholders (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Reconciliation of the Numerator and Denominator used in the Calculation of the Basic and Diluted Earnings per Share	A reconciliation of the numerator and denominator used in the calculation of the basic and diluted net (loss) income per share for the three months ended March 31, 2017 and 2016 is as follows (in thousands, except share and per share amounts): Three Months Ended March 31, 2017 2016 Net (loss) income per share: Numerator Net (loss) income—basic and diluted $ (3,106 ) $ 2,291 Denominator Weighted average shares used to compute net (loss) income —Basic 31,611,841 29,990,006 Potential dilutive stock-based awards, as calculated using treasury stock method — 3,033,489 Weighted average shares used to compute net income —Diluted 31,611,841 33,023,495 Net (loss) income per share —Basic $ (0.10 ) $ 0.08 —Diluted $ (0.10 ) $ 0.07

Geographic Areas and Product 23

Geographic Areas and Product Sales (Tables)	3 Months Ended
Geographic Areas and Product Sales (Tables)	Mar. 31, 2017
Segment Reporting [Abstract]
Revenue by Geographic Area	The Company’s revenue by geographic area, based on the destination to which the Company ships its products, for the three months ended March 31, 2017 and 2016 was as follows (in thousands): Three Months Ended March 31, 2017 2016 United States $ 48,487 $ 39,412 Japan 7,642 6,161 Other International 17,084 12,346 Total $ 73,213 $ 57,919
Revenue by Product Category	The following table sets forth revenue by product category, for the three months ended March 31, 2017 and 2016 was as follows (in thousands): Three Months Ended March 31, 2017 2016 Neuro $ 50,249 $ 41,284 Peripheral Vascular 22,964 16,635 Total $ 73,213 $ 57,919

Organization and Description 24

Organization and Description of Business (Details)	3 Months Ended
Organization and Description of Business (Details)	Mar. 31, 2017market
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of major markets	2

Summary of Significant Accoun25

Summary of Significant Accounting Policies - Additional Disclosures (Details)	3 Months Ended
	Mar. 31, 2017segmentactivity
Accounting Policies [Abstract]
Number of business activities \| activity	1
Number of operating segments \| segment	1

Summary of Significant Accoun26

Summary of Significant Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Condensed Consolidated Balance Sheet Data:
Additional paid-in capital	$ 383,132		$ 273,865
Accumulated deficit	(5,767)		(2,661)
Total stockholder' equity	373,472		$ 266,547
Condensed Consolidated Statements of Operations Data:
Provision for (benefit from) income taxes	1,355	$ (170)
Net (loss) income	$ (3,106)	$ 2,291
Net income per share
Basic (in dollars per share)	$ (0.10)	$ 0.08
Diluted (in dollars per share)	$ (0.10)	$ 0.07
Weighted average shares used to compute net income (loss) per share attributable to common shareholders
Basic (in shares)	31,611,841	29,990,006
Diluted (in shares)	31,611,841	33,023,495
Condensed Consolidated Statement of Cash Flow Data:
Net cash (used in) operating activities	$ 2,194	$ (2,074)
Net cash (used in) financing activities	$ 105,524	(1,513)
Accounting Standards Update 2016-09
Condensed Consolidated Balance Sheet Data:
Additional paid-in capital		253,988
Accumulated deficit		(15,184)
Total stockholder' equity		238,048
Condensed Consolidated Statements of Operations Data:
Provision for (benefit from) income taxes		(170)
Net (loss) income		$ 2,291
Net income per share
Basic (in dollars per share)		$ 0.08
Diluted (in dollars per share)		$ 0.07
Weighted average shares used to compute net income (loss) per share attributable to common shareholders
Basic (in shares)		29,990,006
Diluted (in shares)		33,023,495
Condensed Consolidated Statement of Cash Flow Data:
Net cash (used in) operating activities		$ (2,074)
Net cash (used in) financing activities		(1,513)
As Reported
Condensed Consolidated Balance Sheet Data:
Additional paid-in capital		255,499
Accumulated deficit		(16,695)
Total stockholder' equity		238,048
Condensed Consolidated Statements of Operations Data:
Provision for (benefit from) income taxes		1,341
Net (loss) income		$ 780
Net income per share
Basic (in dollars per share)		$ 0.03
Diluted (in dollars per share)		$ 0.02
Weighted average shares used to compute net income (loss) per share attributable to common shareholders
Basic (in shares)		29,990,006
Diluted (in shares)		32,486,516
Condensed Consolidated Statement of Cash Flow Data:
Net cash (used in) operating activities		$ (3,584)
Net cash (used in) financing activities		$ (3)

Fair Value of Financial Instr27

Fair Value of Financial Instruments (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Financial Assets
Total	$ 208,633	$ 116,390
Commercial paper
Financial Assets
Marketable investments	13,610	4,238
U.S. Treasury
Financial Assets
Marketable investments	9,003	4,996
U.S. agency securities
Financial Assets
Marketable investments	6,837	8,794
U.S. states and municipalities
Financial Assets
Marketable investments	12,678	27,355
Corporate bonds
Financial Assets
Marketable investments	78,926	68,925
Non-U.S. government debt securities
Financial Assets
Marketable investments	1,202	1,209
Commercial Paper
Financial Assets
Cash equivalents	21,769
Money market funds
Financial Assets
Cash equivalents	55,608	873
U.S. agency securities
Financial Assets
Cash equivalents	5,000
Corporate bonds
Financial Assets
Cash equivalents	4,000
Level 1
Financial Assets
Total	64,611	5,869
Level 1 \| Commercial paper
Financial Assets
Marketable investments	0	0
Level 1 \| U.S. Treasury
Financial Assets
Marketable investments	9,003	4,996
Level 1 \| U.S. agency securities
Financial Assets
Marketable investments	0	0
Level 1 \| U.S. states and municipalities
Financial Assets
Marketable investments	0	0
Level 1 \| Corporate bonds
Financial Assets
Marketable investments	0	0
Level 1 \| Non-U.S. government debt securities
Financial Assets
Marketable investments	0	0
Level 1 \| Commercial Paper
Financial Assets
Cash equivalents	0
Level 1 \| Money market funds
Financial Assets
Cash equivalents	55,608	873
Level 1 \| U.S. agency securities
Financial Assets
Cash equivalents	0
Level 1 \| Corporate bonds
Financial Assets
Cash equivalents	0
Level 2
Financial Assets
Total	144,022	110,521
Level 2 \| Commercial paper
Financial Assets
Marketable investments	13,610	4,238
Level 2 \| U.S. Treasury
Financial Assets
Marketable investments		0
Level 2 \| U.S. agency securities
Financial Assets
Marketable investments	6,837	8,794
Level 2 \| U.S. states and municipalities
Financial Assets
Marketable investments	12,678	27,355
Level 2 \| Corporate bonds
Financial Assets
Marketable investments	78,926	68,925
Level 2 \| Non-U.S. government debt securities
Financial Assets
Marketable investments	1,202	1,209
Level 2 \| Commercial Paper
Financial Assets
Cash equivalents	21,769
Level 2 \| Money market funds
Financial Assets
Cash equivalents	0	0
Level 2 \| U.S. agency securities
Financial Assets
Cash equivalents	5,000
Level 2 \| Corporate bonds
Financial Assets
Cash equivalents	4,000
Level 3
Financial Assets
Total	0	0
Level 3 \| Commercial paper
Financial Assets
Marketable investments	0	0
Level 3 \| U.S. Treasury
Financial Assets
Marketable investments	0	0
Level 3 \| U.S. agency securities
Financial Assets
Marketable investments	0	0
Level 3 \| U.S. states and municipalities
Financial Assets
Marketable investments	0	0
Level 3 \| Corporate bonds
Financial Assets
Marketable investments	0	0
Level 3 \| Non-U.S. government debt securities
Financial Assets
Marketable investments	0	0
Level 3 \| Commercial Paper
Financial Assets
Cash equivalents	0
Level 3 \| Money market funds
Financial Assets
Cash equivalents	0	$ 0
Level 3 \| U.S. agency securities
Financial Assets
Cash equivalents	0
Level 3 \| Corporate bonds
Financial Assets
Cash equivalents	$ 0

Balance Sheet Components - Cas

Balance Sheet Components - Cash and Cash Equivalents Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)financial_instituion	Dec. 31, 2016USD ($)
Concentration Risk [Line Items]
Cash, uninsured amount \| $	$ 3.5	$ 2.1
United States
Concentration Risk [Line Items]
Number of financial institutions holding cash in excess of federally insured limits \| financial_instituion	1

Balance Sheet Components - Rest

Balance Sheet Components - Restricted Cash Narrative (Details) $ in Thousands	Mar. 31, 2017USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Restricted cash	$ 1,704

Balance Sheet Components - Acco

Balance Sheet Components - Accounts Receivable, Net (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at Beginning of Period	$ 684	$ 589	$ 589
Charged to Costs and Expenses	145	$ 11	216
Deductions	0		(121)
Balance at End of Period	$ 829		$ 684

Balance Sheet Components - Ac31

Balance Sheet Components - Accounts Receivable Narrative (Details) - Customer Concentration Risk - customer	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, number of customers that accounted for greater than a specified benchmark	0		0
Concentration risk, percentage	10.00%		10.00%
One Major Customer \| Revenue
Concentration Risk [Line Items]
Concentration risk, number of customers that accounted for greater than a specified benchmark	1	1
Concentration risk, percentage	10.00%	11.00%

Balance Sheet Components - Prep

Balance Sheet Components - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Prepaid Tax	$ 1,887	$ 4,656
Prepaid expenses	4,871	4,573
Income tax receivable	4,587	4,536
Other current assets	3,209	4,962
Prepaid expenses and other current assets	$ 14,554	$ 18,727

Balance Sheet Components - Gain

Balance Sheet Components - Gains and Losses of Marketable Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 122,352	$ 115,683
Gross Unrealized Gains	37	41
Gross Unrealized Losses	(133)	(207)
Fair Value	122,256	115,517
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Cost	13,610	4,237
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(1)	0
Fair Value	13,610	4,238
U.S. Treasury
Schedule of Available-for-sale Securities [Line Items]
Cost	9,002	4,996
Gross Unrealized Gains	4	0
Gross Unrealized Losses	(3)	0
Fair Value	9,003	4,996
U.S. agency securities
Schedule of Available-for-sale Securities [Line Items]
Cost	6,847	8,803
Gross Unrealized Gains	0	3
Gross Unrealized Losses	(10)	(12)
Fair Value	6,837	8,794
U.S. states and municipalities
Schedule of Available-for-sale Securities [Line Items]
Cost	12,687	27,429
Gross Unrealized Gains	2	1
Gross Unrealized Losses	(11)	(75)
Fair Value	12,678	27,355
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Cost	79,004	69,009
Gross Unrealized Gains	30	36
Gross Unrealized Losses	(108)	(120)
Fair Value	78,926	68,925
Non-U.S. government debt securities
Schedule of Available-for-sale Securities [Line Items]
Cost	1,202	1,209
Gross Unrealized Gains	0	0
Gross Unrealized Losses		0
Fair Value	$ 1,202	$ 1,209

Balance Sheet Components - Mark

Balance Sheet Components - Marketable Securities in an Unrealized Loss Position (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 71,551,000	$ 55,325,000
Gross Unrealized Losses, less than 12 months	(133,000)	(207,000)
Gross Unrealized Losses, greater than 12 months	0	0
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Fair Value	7,977,000
Gross Unrealized Losses, less than 12 months	(1,000)
U.S. agency securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	4,892,000	3,291,000
Gross Unrealized Losses, less than 12 months	(10,000)	(12,000)
U.S. states and municipalities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	9,947,000	22,286,000
Gross Unrealized Losses, less than 12 months	(11,000)	(75,000)
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Fair Value	43,741,000	29,748,000
Gross Unrealized Losses, less than 12 months	$ (108,000)	$ (120,000)

Balance Sheet Components - Cont

Balance Sheet Components - Contractual Maturities of Marketable Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Due in one year	$ 105,348	$ 71,051
Due in one to five years	16,908	44,466
Total	$ 122,256	$ 115,517

Balance Sheet Components - Inve

Balance Sheet Components - Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials	$ 9,910	$ 11,367
Work in process	4,420	3,663
Finished goods	64,857	57,982
Inventories	$ 79,187	$ 73,012

Balance Sheet Components - Prop

Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 30,558		$ 28,485
Less: Accumulated depreciation and amortization	(7,653)		(7,021)
Property and equipment, net	22,905		21,464
Depreciation and amortization expense	654	$ 538
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	10,457		9,734
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	4,598		4,246
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	10,291		10,207
Software
Property, Plant and Equipment [Line Items]
Total property and equipment	1,641		1,221
Computers
Property, Plant and Equipment [Line Items]
Total property and equipment	1,118		884
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 2,453		$ 2,193

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Payroll and employee-related cost	$ 19,223	$ 16,956
Sales return reserve	2,940	2,753
Preclinical and clinical trial cost	1,877	2,054
Deferred revenue	357	344
Product warranty	1,087	1,254
Sales tax and VAT payable	548	733
Income tax payable	354	174
Other accrued liabilities	7,205	7,422
Total accrued liabilities	$ 33,591	$ 31,690

Balance Sheet Components - Prod

Balance Sheet Components - Product Warranty (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Product Warranty, Increase (Decrease) [Roll Forward]
Balance at the beginning of the period	$ 1,254	$ 713
Accruals of warranties issued	39	1,176
Settlements of warranty claims	(206)	(635)
Balance at the end of the period	$ 1,087	$ 1,254

Commitments and Contingencies -

Commitments and Contingencies - Lease and Purchase Commitments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Rent expense	$ 1.4	$ 1.1

Commitments and Contingencies41

Commitments and Contingencies - Royalty Obligations (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Cost of Sales
Other Commitments [Line Items]
Royalty expense	$ 800,000	$ 700,000
Royalty Agreement, March 2005
Other Commitments [Line Items]
Minimum annual royalty payments	$ 100,000		$ 100,000
Royalty Agreement, April 2012
Other Commitments [Line Items]
Royalty as a percent of sales	5.00%
Royalty Agreement, November 2013, Less than $5 Million in Sales
Other Commitments [Line Items]
Royalty as a percent of sales	3.00%
Royalty Agreement, November 2013, Greater than $5 Million in Sales
Other Commitments [Line Items]
Royalty as a percent of sales	1.00%
Royalty threshold	$ 5,000,000
Royalty Agreement, April 2015
Other Commitments [Line Items]
Royalty as a percent of sales	2.00%

Commitments and Contingencies42

Commitments and Contingencies - Litigation (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)
Damages from Product
Loss Contingencies [Line Items]
Damages sought, value	$ 35

Stockholder's Equity - Common S

Stockholder's Equity - Common Stock (Details) - Underwritten Public Offering $ / shares in Units, $ in Millions	1 Months Ended
	Mar. 31, 2017USD ($)$ / sharesshares
Subsidiary, Sale of Stock [Line Items]
Number of shares issued and sold (in shares) \| shares	1,495,000
Public offering price (in USD per share) \| $ / shares	$ 76
Net cash proceeds from shares issued and sold	$ 106.3
Underwriting discounts and commissions	6.8
Other offering expenses	$ 0.5

Stockholder's Equity - Stock Op

Stockholder's Equity - Stock Option Activity (Details)	3 Months Ended
Stockholder's Equity - Stock Option Activity (Details)	Mar. 31, 2017$ / sharesshares
Number of Shares
Beginning balance (in shares) \| shares	2,876,955
Options exercised (in shares) \| shares	(383,457)
Options cancelled (in shares) \| shares	(969)
Ending balance (in shares) \| shares	2,492,529
Weighted- Average Exercise Price
Beginning balance (in dollars per share) \| $ / shares	$ 14.63
Options exercised (in dollars per share) \| $ / shares	2.73
Options cancelled (in dollars per share) \| $ / shares	10.56
Ending balance (in dollars per share) \| $ / shares	$ 16.47

Stockholder's Equity - Restrict

Stockholder's Equity - Restricted Stock and Restricted Stock Units Activity (Details) - Restricted stock and restricted stock units	3 Months Ended
	Mar. 31, 2017$ / sharesshares
Number of Shares
Unvested beginning balance (in shares) \| shares	1,002,944
Granted (in shares) \| shares	58,660
Vested (in shares) \| shares	(115,685)
Canceled/Forfeited (in shares) \| shares	(18,125)
Unvested and expected to vest ending balance (in shares) \| shares	927,794
Weighted Average Grant Date Fair Value
Unvested beginning balance (in dollars per share) \| $ / shares	$ 29.44
Granted (in dollars per share) \| $ / shares	76.47
Vested (in dollars per share) \| $ / shares	15.63
Canceled/Forfeited (in dollars per share) \| $ / shares	41.31
Unvested and expected to vest ending balance (in dollars per share) \| $ / shares	$ 25.84

Stockholder's Equity - Stock-ba

Stockholder's Equity - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 4,012	$ 3,015
Unrecognized compensation cost related to unvested share-based compensation arrangements	$ 34,600
Unrecognized compensation cost, expected recognition period	2 years 8 months 12 days
Share-based compensation expense, capitalized in inventory	$ 400		$ 400
Cost of sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	309	9
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	253	258
Sales, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 3,450	$ 2,748

Accumulated Other Comprehensi47

Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 266,547
Other comprehensive income before reclassifications:
Income tax effect—benefit (expense)	0	$ (155)
Net of tax	793	1,329
Amounts reclassified from accumulated other comprehensive income to earnings:
Realized losses (gains)—marketable investments	(31)	0
Income tax effect—(expense) benefit	0	0
Net of tax	(31)	0
Net current-year other comprehensive income	762	1,329
Ending balance	373,472
Marketable Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(105)	(163)
Other comprehensive income before reclassifications:
Other comprehensive income before reclassifications	101	441
Income tax effect—benefit (expense)	0	(160)
Net of tax	101	281
Amounts reclassified from accumulated other comprehensive income to earnings:
Realized losses (gains)—marketable investments	(31)	0
Income tax effect—(expense) benefit	0	0
Net of tax	(31)	0
Net current-year other comprehensive income	70	281
Ending balance	(35)	118
Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(4,583)	(1,952)
Other comprehensive income before reclassifications:
Other comprehensive income before reclassifications	692	1,043
Income tax effect—benefit (expense)	0	5
Net of tax	692	1,048
Amounts reclassified from accumulated other comprehensive income to earnings:
Realized losses (gains)—marketable investments	0	0
Income tax effect—(expense) benefit	0	0
Net of tax	0	0
Net current-year other comprehensive income	692	1,048
Ending balance	(3,891)	(904)
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(4,688)	(2,115)
Amounts reclassified from accumulated other comprehensive income to earnings:
Ending balance	$ (3,926)	$ (786)

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Effective tax rate	(77.40%)	(8.00%)
Cumulative income period			3 years
Excess tax deduction	$ 1.5		$ 74.9
Deferred tax assets, valuation allowance	$ 9.8

Net (Loss) Income per Share o49

Net (Loss) Income per Share of Common Stock attributable to Common Stockholders - Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator
Net (loss) income	$ (3,106)	$ 2,291
Less: Undistributed income attributable to preferred stockholders-diluted	0	0
Net (loss) income attributable to common stockholders-basic	(3,106)	2,291
Net (loss) income attributable to common stockholders-diluted	$ (3,106)	$ 2,291
Denominator
Weighted average shares used to compute net (loss) income per share attributable to common stockholders — Basic (in shares)	31,611,841	29,990,006
Weighted average shares used to compute net income attributable to common stockholders —Diluted (in shares)	31,611,841	33,023,495
Net (loss) income per share attributable to common stockholders — Basic (in dollars per share)	$ (0.10)	$ 0.08
Net (loss) income per share attributable to common stockholders — Diluted (in dollars per share)	$ (0.10)	$ 0.07
Options and ESPP Shares
Denominator
Potential dilutive shares(in shares)	0	3,033,489

Net (Loss) Income per Share o50

Net (Loss) Income per Share of Common Stock attributable to Common Stockholders - Antidilutive Securities (Details) - shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from the computation of earnings per share (in shares)	3,500,000	12,500

Geographic Areas and Product 51

Geographic Areas and Product Sales - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 73,213	$ 57,919
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	48,487	39,412
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	7,642	6,161
Other International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 17,084	$ 12,346

Geographic Areas and Product 52

Geographic Areas and Product Sales - Revenue by Product Category (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenue from External Customer [Line Items]
Revenue	$ 73,213	$ 57,919
Neuro
Revenue from External Customer [Line Items]
Revenue	50,249	41,284
Peripheral Vascular
Revenue from External Customer [Line Items]
Revenue	$ 22,964	$ 16,635