Penumbra (PEN) 10-Q 7 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 23, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	Penumbra Inc
Entity Central Index Key	0001321732
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		34,737,497

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 95,606	$ 67,850
Marketable investments	99,241	133,039
Accounts receivable, net of doubtful accounts of $2,877 and $2,782 at March 31, 2019 and December 31, 2018, respectively	94,679	81,896
Inventories	121,691	115,741
Prepaid expenses and other current assets	11,869	12,200
Total current assets	423,086	410,726
Property and equipment, net	35,380	35,407
Operating lease right-of-use asset	42,376	0
Intangible assets, net	26,813	27,245
Goodwill	7,659	7,813
Deferred taxes	31,862	32,940
Other non-current assets	1,613	875
Total assets	568,789	515,006
Current liabilities:
Accounts payable	7,692	8,176
Accrued liabilities	58,032	57,886
Current operating lease liabilities	3,688	0
Total current liabilities	69,412	66,062
Deferred rent	0	7,586
Non-current operating lease liabilities	46,070	0
Other non-current liabilities	16,644	18,943
Total liabilities	132,126	92,591
Commitments and contingencies
Stockholders’ equity:
Common stock	34	34
Additional paid-in capital	419,514	415,084
Accumulated other comprehensive loss	(2,578)	(1,942)
Retained earnings	19,762	9,064
Total Penumbra, Inc. stockholders’ equity	436,732	422,240
Non-controlling interest	(69)	175
Total stockholders’ equity	436,663	422,415
Total liabilities and stockholders’ equity	$ 568,789	$ 515,006

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($)	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Accumulated Deficit)	Total Penumbra, Inc. Stockholders’ Equity	Non-controlling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total stockholders’ equity	$ 400,408,000	$ 33,000	$ 396,810,000	$ 1,569,000	$ 1,996,000	$ 400,408,000
Beginning balance (in shares) at Dec. 31, 2017		33,685,146
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, New Issues	5,256,000	$ 0	5,256,000			5,256,000
Shares issued (in shares)		53,256
Issuance of common stock (in shares)		232,943
Issuance of common stock	1,329,000	$ 1,000	1,328,000			1,329,000
Shares held for tax withholdings	(3,530,000)		(3,530,000)			(3,530,000)
Shares held for tax withholdings (in shares)		38,677
Stock-based compensation	4,435,000		4,435,000			4,435,000
Other comprehensive loss	1,068,000			1,068,000		1,068,000
Net income attributable to Penumbra, Inc.	5,491,000				5,491,000	5,491,000
Net loss attributable to non-controlling interest	0						$ 0
Consolidated net income	5,491,000
Ending balance (in shares) at Mar. 31, 2018		33,932,668
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total stockholders’ equity	414,921,000	$ 34,000	404,299,000	2,637,000	7,951,000	414,921,000	0
Total stockholders’ equity	422,415,000	$ 34,000	415,084,000	(1,942,000)	9,064,000	422,240,000	175,000
Beginning balance (in shares) at Dec. 31, 2018		34,437,339
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		140,598
Issuance of common stock	1,071,000	$ 0	1,071,000			1,071,000
Shares held for tax withholdings	(2,098,000)		(2,098,000)			(2,098,000)
Shares held for tax withholdings (in shares)		14,284
Stock-based compensation	5,457,000		5,457,000			5,457,000
Other comprehensive loss	(636,000)			(636,000)		(636,000)
Net income attributable to Penumbra, Inc.	10,698,000				10,698,000	10,698,000
Net loss attributable to non-controlling interest	(244,000)						(244,000)
Consolidated net income	10,454,000
Ending balance (in shares) at Mar. 31, 2019		34,563,653
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total stockholders’ equity	436,663,000	$ 34,000	$ 419,514,000	$ (2,578,000)	$ 19,762,000	$ 436,732,000	$ (69,000)
Cumulative effect adjustments	$ 0

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 2,877	$ 2,782

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Revenues	$ 128,439	$ 102,701
Cost of revenue	44,529	36,144
Gross profit	83,910	66,557
Operating expenses:
Research and development	11,667	8,013
Sales, general and administrative	61,091	54,499
Total operating expenses	72,758	62,512
Income from operations	11,152	4,045
Interest income, net	733	749
Other income (expense), net	24	(290)
Income before income taxes and equity in losses of unconsolidated investee	11,909	4,504
Provision for (benefit from) income taxes	1,455	(1,938)
Income before equity in losses of unconsolidated investee	10,454	6,442
Equity in losses of unconsolidated investee	0	(951)
Consolidated net income	10,454	5,491
Net loss attributable to non-controlling interest	(244)	0
Net income attributable to Penumbra, Inc.	$ 10,698	$ 5,491
Net (loss) income per share attributable to common stockholders — Basic (in dollars per share)	$ 0.31	$ 0.16
Net (loss) income per share attributable to common stockholders — Diluted (in dollars per share)	$ 0.30	$ 0.15
Weighted average shares used to compute net (loss) income per share attributable to common stockholders — Basic (in shares)	34,507,279	33,846,142
Weighted average shares used to compute net (loss) income per share attributable to common stockholders — Diluted (in shares)	36,213,164	35,917,051

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Consolidated net income	$ 10,454	$ 5,491
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments, net of tax	(1,098)	1,386
Net change in unrealized gains (losses) on available-for-sale securities, net of tax	462	(318)
Total other comprehensive (loss) income, net of tax	(636)	1,068
Consolidated comprehensive income	9,818	6,559
Net loss attributable to non-controlling interest	(244)	0
Comprehensive income attributable to Penumbra, Inc.	$ 10,062	$ 6,559

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Cash Flows [Abstract]
Net income	$ 10,454	$ 5,491
Adjustments to reconcile consolidated net income to net cash (used in) provided by operating activities:
Depreciation and amortization	1,804	1,399
Stock-based compensation	5,095	4,154
Loss on non-marketable equity investments	0	951
Inventory write-downs	658	300
Deferred taxes	1,078	(2,209)
Change in fair value of contingent consideration	0	442
Other	396	389
Changes in operating assets and liabilities:
Accounts receivable	(13,373)	(6,109)
Inventories	(6,728)	208
Prepaid expenses and other current and non-current assets	45	2,986
Accounts payable	(1,503)	622
Accrued expenses and other non-current liabilities	6	2,084
Net cash (used in) provided by operating activities	(2,068)	10,708
CASH FLOWS FROM INVESTING ACTIVITIES:
Contributions to non-marketable investments	0	(352)
Purchases of marketable investments	0	(42,552)
Proceeds from sales of marketable investments	1,018	0
Proceeds from maturities of marketable investments	33,300	43,540
Purchases of property and equipment	(2,463)	(2,823)
Net cash provided by (used in) investing activities	31,855	(2,187)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercises of stock options	1,071	1,328
Payment of employee taxes related to vested common and restricted stock	(2,098)	(3,530)
Payment of acquisition-related obligations	(683)	(4,323)
Proceeds from capital contribution from non-controlling interest	0	(219)
Net cash used in financing activities	(1,710)	(6,744)
Effect of foreign exchange rate changes on cash and cash equivalents	(321)	391
NET INCREASE IN CASH AND CASH EQUIVALENTS	27,756	2,168
CASH AND CASH EQUIVALENTS—Beginning of period	67,850	50,637
CASH AND CASH EQUIVALENTS—End of period	95,606	52,805
NONCASH INVESTING AND FINANCING ACTIVITIES:
Common shares issued as consideration in connection with a buyout agreement (Notes 9 and 10)	0	5,256
Purchase of property and equipment funded through accounts payable and accrued liabilities	$ 860	$ 427

Organization and Description of

Organization and Description of Business	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	1. Organization and Description of Business Penumbra, Inc. (the “Company”) is a global healthcare company focused on innovative therapies. The Company designs, develops, manufactures and markets medical devices and has a broad portfolio of products that addresses challenging medical conditions and significant clinical needs.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation and Consolidation The accompanying condensed consolidated balance sheet as of March 31, 2019 , the condensed consolidated statements of operations for the three months ended March 31, 2019 and 2018 , the condensed consolidated statements of comprehensive income for the three months ended March 31, 2019 and 2018 , the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2019 and 2018 , and the condensed consolidated statements of cash flows for the three months ended March 31, 2019 and 2018 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 U.S. 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, 2018 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, 2019 , the results of its operations for the three months ended March 31, 2019 and 2018 , the changes in stockholders’ equity for the three months ended March 31, 2019 and 2018 , and the cash flows for the three months ended March 31, 2019 and 2018 . The results for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 or for any other future annual or interim period. 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, 2018 , 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, 2019 , 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, 2018 , other than changes to the Company’s leasing policy described below in connection with the adoption of the guidance under Accounting Standards Codification (“ASC”) 842. The condensed consolidated financial statements include the accounts of the Company, its wholly-owned subsidiaries and its majority-owned subsidiary. The portion of equity not attributable to the Company is considered non-controlling interest and is classified separately in the condensed consolidated financial statements. Any subsequent changes in the Company’s ownership interest while the Company retains its controlling interest in its majority-owned subsidiary will be accounted for as equity transactions. All intercompany balances and transactions have been eliminated in consolidation. 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, the amount of variable consideration included in the transaction price, warranty reserve, valuation of inventories, useful lives of property and equipment, operating lease right-of-use (“ROU”) assets and liabilities, income taxes, contingent consideration and other 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. Recently Adopted Accounting Standards On January 1, 2019, the Company adopted Accounting Standard Update (“ASU”) No. 2016-02 , Leases (Topic 842) , and its associated amendments using the modified retrospective transition approach by applying the new standard to all leases existing at the date of initial application and not restating comparative periods. There was no cumulative-effect adjustment recorded to retained earnings upon adoption. Under the standard, a lessee is required to recognize a lease liability and ROU asset for all leases. The new guidance also modified the classification criteria 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 continues to depend primarily on its classification. The Company elected the package of practical expedients permitted under the transition guidance, which allowed the Company to carryforward its historical lease classification, its assessment on whether a contract was or contains a lease, and its initial direct costs for any leases that existed prior to January 1, 2019. In addition, the Company elected the following transitional practical expedients: (1) the short-term lease exception and (2) to not separate its non-lease components for its real estate, vehicle and equipment leases. The impact of adoption and additional disclosures required by the ASU have been included in “Significant Accounting Policies - Leases” below and in Note “ 8. Leases .” Significant Accounting Policies - Leases The Company adopted the guidance under ASC 842 on January 1, 2019 using the modified retrospective transition approach. There was no cumulative-effect adjustment recorded to retained earnings upon adoption. Under ASC 842, the Company determines if an arrangement is a lease at inception. In addition, the Company determines whether leases meet the classification criteria of a finance or operating lease at the lease commencement date considering: (1) whether the lease transfers ownership of the underlying asset to the lessee at the end of the lease term, (2) whether the lease contains a bargain purchase option, (3) whether the lease term is for a major part of the remaining economic life of the underlying asset, (4) whether the present value of the sum of the lease payments and residual value guaranteed by the lessee equals or exceeds substantially all of the fair value of the underlying asset, and (5) whether the underlying asset is of such a specialized nature that it is expected to have no alternative use to the lessor at the end of the lease term. As of March 31, 2019, the Company's contracts that contained a lease consisted of real estate, equipment and vehicle leases. As of the date of adoption of ASC 842 and March 31, 2019, the Company did not have material finance leases. Operating leases are included in operating lease right-of-use assets, current operating lease liabilities, and non-current operating lease liabilities in our condensed consolidated balance sheet. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the present value of lease payments, the Company uses its incremental borrowing rate based on the information available at the lease commencement date if the rate implicit in the lease is not readily determinable. The determination of the Company’s incremental borrowing rate requires management judgment including, the development of a synthetic credit rating and cost of debt as the Company currently does not carry any debt. The operating lease ROU assets also include adjustments for prepayments, accrued lease payments and exclude lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise such options. Operating lease cost is recognized on a straight-line basis over the expected lease term. Lease agreements entered into after the adoption of ASC 842 that include lease and non-lease components are accounted for as a single lease component. Lease agreements with a noncancelable term of less than 12 months are not recorded on the Company’s condensed consolidated balance sheet. For more information about the impact of adoption and disclosures on the Company’s leases, refer to Note “ 8. Leases .” 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 devices, and operates as one operating segment. The Company’s chief operating decision-maker, its Chief Executive Officer, reviews its consolidated operating results for the purpose of allocating resources and evaluating financial performance. Recent Accounting Guidance Recently Issued Accounting Standards In June 2016, the Financial Accounting Standards Board (“ 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. In April 2019, the FASB issued ASU No. 2019-04 which provides additional clarification and address stakeholders’ specific issues about certain aspects of the amendments in the previously issued ASU No. 2016-13. 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 August 2018, the FASB issued ASU 2018-13, Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement . The primary focus of the standard is to improve the effectiveness of the disclosure requirements for fair value measurements. The standard is effective for fiscal years and interim periods beginning after December 15, 2019. An entity is permitted to early adopt the removed or modified disclosures upon the issuance of the standard and may delay adoption of the additional disclosures until their effective date. The Company is currently evaluating the impact of adopting this standard.

Investments and Fair Value of F

Investments and Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	3. Investments and Fair Value of Financial Instruments Marketable Investments The Company’s marketable investments have been classified and accounted for as available-for-sale. The following table presents the Company’s marketable investments as of March 31, 2019 and December 31, 2018 (in thousands): March 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 1,500 $ — $ — $ 1,500 U.S. treasury 2,400 — (9 ) 2,391 U.S. agency and government sponsored securities 7,708 21 (14 ) 7,715 U.S. states and municipalities 3,631 1 — 3,632 Corporate bonds 84,039 94 (130 ) 84,003 Total $ 99,278 $ 116 $ (153 ) $ 99,241 December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 13,701 $ — $ (3 ) $ 13,698 U.S. treasury 6,400 — (22 ) 6,378 U.S. agency and government sponsored securities 7,699 18 (27 ) 7,690 U.S. states and municipalities 5,134 — (12 ) 5,122 Corporate bonds 100,606 14 (469 ) 100,151 Total $ 133,540 $ 32 $ (533 ) $ 133,039 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 or for twelve months or more as of March 31, 2019 and December 31, 2018 (in thousands): March 31, 2019 Less than 12 months 12 months or more Total Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses U.S. treasury $ — $ — $ 2,391 $ (9 ) $ 2,391 $ (9 ) U.S. agency and government sponsored securities — — 4,211 (14 ) 4,211 (14 ) Corporate bonds 8,307 (6 ) 31,435 (124 ) 39,742 (130 ) Total $ 8,307 $ (6 ) $ 38,037 $ (147 ) $ 46,344 $ (153 ) December 31, 2018 Less than 12 months 12 months or more Total Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Commercial paper $ 12,208 $ (3 ) $ — $ — $ 12,208 $ (3 ) U.S. treasury — — 6,378 (22 ) 6,378 (22 ) U.S. agency and government sponsored securities 1,436 (5 ) 2,759 (22 ) 4,195 (27 ) U.S. states and municipalities 1,529 (5 ) 3,593 (7 ) 5,122 (12 ) Corporate bonds 58,961 (176 ) 33,215 (293 ) 92,176 (469 ) Total $ 74,134 $ (189 ) $ 45,945 $ (344 ) $ 120,079 $ (533 ) The following table presents the contractual maturities of the Company’s marketable investments as of March 31, 2019 and December 31, 2018 (in thousands): March 31, 2019 December 31, 2018 Fair Value Fair Value Due in less than one year $ 53,205 $ 83,391 Due in one to five years 46,036 49,648 Total $ 99,241 $ 133,039 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. Financial instruments 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, or 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 following tables set forth the Company’s financial assets measured at fair value by level within the fair value hierarchy as of March 31, 2019 and December 31, 2018 (in thousands): As of March 31, 2019 Level 1 Level 2 Level 3 Fair Value Financial Assets Cash equivalents: Money market funds $ 44,331 $ — $ — $ 44,331 Marketable investments: Commercial paper — 1,500 — 1,500 U.S. treasury 2,391 — — 2,391 U.S. agency and government sponsored securities — 7,715 — 7,715 U.S. states and municipalities — 3,632 — 3,632 Corporate bonds — 84,003 — 84,003 Total $ 46,722 $ 96,850 $ — $ 143,572 Financial Liabilities: Contingent consideration obligations (1) $ — $ — $ 1,248 $ 1,248 Total $ — $ — $ 1,248 $ 1,248 (1) More information on the contingent consideration obligations and the changes in fair value are presented below. As of December 31, 2018 Level 1 Level 2 Level 3 Fair Value Financial Assets Cash equivalents: Commercial paper $ — $ 10,967 $ — $ 10,967 Money market funds 12,087 — — 12,087 Marketable investments: Commercial paper — 13,698 — 13,698 U.S. treasury 6,378 — — 6,378 U.S. agency and government sponsored securities — 7,690 — 7,690 U.S. states and municipalities — 5,122 — 5,122 Corporate bonds — 100,151 — 100,151 Total $ 18,465 $ 137,628 $ — $ 156,093 Financial Liabilities: Contingent consideration obligations (1) $ — $ — $ 2,571 $ 2,571 Total $ — $ — $ 2,571 $ 2,571 (1) More information on the contingent consideration obligations and the changes in fair value are presented below. Contingent Consideration Obligations As of March 31, 2019 and December 31, 2018 , the Company’s contingent consideration liability relates to milestone payments due in connection with the acquisition of Crossmed and is classified as a Level 3 measurement for which fair value is derived from various inputs, including forecasted revenues during the earn-out milestone periods, revenue volatilities, discount rates, and estimates in the likelihood of achieving revenue-based milestones. The fair value of the contingent consideration liability is remeasured each reporting period. The following table presents quantitative information about certain unobservable inputs used in the Level 3 fair value measurement of the Company’s contingent consideration liability, other than the forecasted revenues during the earn-out milestone period: Fair Value at March 31, 2019 (in thousands) Valuation Method Unobservable Inputs Input (range where applicable) Crossmed: Revenue-based milestones $ 1,248 Monte Carlo Simulation Earn-out period over which revenue-based milestone payments are made 2019 Risk-adjusted discount rate 15% Revenue volatilities for each type of revenue-based milestone 5.1% and 18.4% The following tables summarize the changes in fair value of the contingent consideration obligation for the three months ended March 31, 2019 and March 31, 2018 (in thousands): Fair Value of Contingent Consideration Balance at December 31, 2018 $ 2,571 Payments of contingent consideration liabilities (1,296 ) Changes in fair value — Foreign currency remeasurement (27 ) Balance at March 31, 2019 $ 1,248 Fair Value of Contingent Consideration Balance at December 31, 2017 $ 4,675 Payments of contingent consideration liabilities (3,017 ) Changes in fair value 442 Foreign currency remeasurement 133 Balance at March 31, 2018 $ 2,233 During the three months ended March 31, 2019 , the were no changes to the fair value of the contingent consideration obligation. During the three months ended March 31, 2018 , the fair value of the contingent consideration obligation increased by $0.4 million which was recorded in sales, general and administrative expense in the condensed consolidated statements of operations. The fair value of the contingent consideration increased as a result of updates to the underlying forecasts based on actual results to date and changes in estimates. For more information related to the payment of the contingent consideration liabilities refer to Note “ 5. Asset Acquisitions and Business Combinations .” During the three months ended March 31, 2019 and 2018 , the Company did not record impairment charges related to its marketable investments and the Company did not hold any Level 3 marketable investments as of March 31, 2019 or December 31, 2018 . During the three months ended March 31, 2019 and 2018 , the Company did not have any transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy. Additionally, the Company did not have any financial assets and liabilities measured at fair value on a non-recurring basis as of March 31, 2019 or December 31, 2018 .

Balance Sheet Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	4. Balance Sheet Components Inventories The following table shows the components of inventories as of March 31, 2019 and December 31, 2018 (in thousands): March 31, December 31, Raw materials $ 18,968 $ 18,829 Work in process 12,502 10,630 Finished goods 90,221 86,282 Inventories $ 121,691 $ 115,741 Accrued Liabilities The following table shows the components of accrued liabilities as of March 31, 2019 and December 31, 2018 (in thousands): March 31, December 31, Payroll and employee-related cost $ 31,940 $ 33,838 Accrued expenses 5,094 4,088 Sales return provision 2,269 2,986 Product warranty 2,077 1,875 Contingent consideration & other acquisition-related costs (1) 4,611 4,439 Other accrued liabilities 12,041 10,660 Total accrued liabilities $ 58,032 $ 57,886 (1) Amount consists of the current portion of contingent liabilities related to (1) the cash milestone payments and working capital adjustment liabilities for the 2017 acquisition of Crossmed and (2) an anti-dilution provision for the 2018 asset acquisition of MVI. Refer to Note “ 5. Asset Acquisitions and Business Combinations ” for more information on the acquisition of Crossmed and asset acquisition of MVI. The following table shows the changes in the Company’s estimated product warranty accrual, included in accrued liabilities, as of March 31, 2019 and December 31, 2018 (in thousands): March 31, December 31, Balance at the beginning of the period $ 1,875 $ 1,088 Accruals of warranties issued 355 1,336 Settlements of warranty claims (153 ) (549 ) Balance at the end of the period $ 2,077 $ 1,875 Other Non-Current Liabilities The following table shows the components of other non-current liabilities as of March 31, 2019 and December 31, 2018 (in thousands): March 31, December 31, Deferred tax liabilities $ 3,972 $ 4,171 Licensing-related cost (1) 11,463 11,506 Asset acquisition-related costs (2) 1,000 2,500 Other non-current liabilities 209 766 Total other non-current liabilities $ 16,644 $ 18,943 (1) Amount relates to the non-current liability recorded for probable future milestone payments to be made under the licensing agreement described in Note “ 6. Intangible Assets .” Refer therein for more information. (2) Asset acquisition-related costs represents the non-current portion of the probable contingent liability related to an anti-dilution provision for the 2018 asset acquisition of MVI.

Asset Acquisitions & Business C

Asset Acquisitions & Business Combination	3 Months Ended
	Mar. 31, 2019
Business Combinations [Abstract]
Asset Acquisitions and Business Combinations	5. Asset Acquisitions and Business Combinations Payments Related to 2017 Crossmed Acquisition On July 3, 2017, the Company completed its acquisition of Crossmed, a joint stock company organized under the laws of Italy. As of March 31, 2019 and December 31, 2018 , the Company’s condensed consolidated balance sheet included $1.3 million and $2.6 million , respectively, in current liabilities primarily related to additional consideration due to the sellers of Crossmed (the “Sellers”) for revenue-based milestone payments, based on net revenue in the years ending December 31, 2018 and 2019, and other working capital and financial debt adjustments. During the three months ended March 31, 2019 , the Company made $1.3 million in milestone payments of which $0.6 million is presented in operating activities and $0.7 million is presented in financing activities in the condensed consolidated statement of cash flows. During the three months ended March 31, 2018 , the Company made $4.3 million in payments to the Sellers which is presented in financing activities in the condensed consolidated statement of cash flows. Payments Related to 2018 MVI Asset Acquisition In 2017, the Company and Sixense Enterprises, Inc. (“Sixense”) formed MVI Health Inc. (“MVI”) as a privately-held joint venture for the purpose of exploring healthcare applications of virtual reality technology, with each party holding 50% of the issued and outstanding equity of MVI. On August 31, 2018 (“ Transfer Agreement Closing Date ”), the Company completed its asset acquisition of MVI pursuant to a Stock Transfer Agreement (the “Transfer Agreement”) between the Company, MVI and Sixense to obtain a controlling interest of MVI for $20.0 million , excluding the additional $4.5 million of probable future payments relating to an anti-dilution provision in the Transfer Agreement. Following the Transfer Agreement Closing Date , the Company owns a 90% controlling interest in MVI and Sixense retains the remaining 10% minority interest. During the year ended December 31, 2018 , the Company contributed $0.5 million to MVI related to the anti-dilution provision. As of December 31, 2018 , the Company’s condensed consolidated balance sheet included $1.5 million and $2.5 million , respectively, in current and non-current liabilities related to the anti-dilution provision in the Transfer Agreement . A s of March 31, 2019 , the Company’s condensed consolidated balance sheet included $3.0 million and $1.0 million , respectively, in current and non-current liabilities related to the anti-dilution provision in the Transfer Agreement.

Intangible Assets

Intangible Assets	3 Months Ended
	Mar. 31, 2019
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets	6. Intangible Assets Acquired Intangible Assets The following tables present details of the Company’s acquired finite-lived and indefinite-lived intangible assets, as of March 31, 2019 and December 31, 2018 (in thousands, except weighted-average amortization period): March 31, 2019 Weighted-Average Amortization Period Gross Carrying Amount Accumulated Amortization Net Customer relationships 15.0 years $ 6,688 $ (781 ) $ 5,907 Trade secrets and processes 20.0 years 5,256 (329 ) 4,927 Other 5.0 years 1,725 (603 ) 1,122 Total intangible assets subject to amortization 16.1 years $ 13,669 $ (1,713 ) $ 11,956 Intangible assets related to licensed technology 14,857 — 14,857 Total intangible assets $ 28,526 $ (1,713 ) $ 26,813 December 31, 2018 Weighted-Average Amortization Period Gross Carrying Amount Accumulated Amortization Net Customer relationships 15.0 years $ 6,823 $ (681 ) $ 6,142 Trade secrets and processes 20.0 years 5,256 (263 ) 4,993 Other 5.0 years 1,759 (528 ) 1,231 Total intangible assets subject to amortization 16.0 years $ 13,838 $ (1,472 ) $ 12,366 Intangible assets related to licensed technology 14,879 — 14,879 Total intangible assets $ 28,717 $ (1,472 ) $ 27,245 The customer relationships and other intangible assets subject to amortization relate to the acquisition of Crossmed during the third quarter of 2017. The gross carrying amount and accumulated amortization of these intangible assets are subject to foreign currency translation effects. Refer to Note “ 5. Asset Acquisitions and Business Combinations ” for more information. The Company’s $5.3 million trade secrets and processes intangible asset was recognized in connection with a royalty buyout agreement during the first quarter of 2018, which is discussed further in Note “ 9. Commitments and Contingencies ” and Note “ 10. Stockholders’ Equity .” The following table presents the amortization expense recorded related to the Company’s finite-lived intangible assets for the three months ended March 31, 2019 and March 31, 2018 (in thousands): Three Months Ended March 31, 2019 2018 Cost of revenue $ 66 $ 31 Sales, general and administrative 200 216 Total $ 266 $ 247 Licensed technology During the third quarter of 2017, the Company entered into an exclusive technology license agreement (the “License Agreement”) that required the Company to pay an upfront payment to the licensor of $2.5 million and future revenue milestone-based payments on sales of products covered by the licensed intellectual property. The Company recorded an intangible asset equal to the total payments made and expected to be made under the License Agreement and a corresponding contingent liability for the probable future milestone payments not yet paid. As of March 31, 2019 , the licensed technology is accounted for as an indefinite-lived intangible asset. Upon the commercialization of the underlying product utilizing the licensed technology, the capitalized amount will be amortized over its estimated useful life. At the end of each reporting period the Company adjusts the contingent liabilities to reflect the amount of future milestone payments that are probable to be paid. Prior to the commercialization of products utilizing the underlying technology, any changes in the contingent liability are recorded as an adjustment between the liability balances and the gross carrying amount of the indefinite-lived intangible asset. During the three months ended March 31, 2019 , there were no material changes to the contingent liability related to the License Agreement. As of March 31, 2019 , the balance of the contingent liability related to probable future milestone payments under the License Agreement was $12.4 million , of which $0.9 million and $11.5 million were included in accrued liabilities and other non-current liabilities on the condensed consolidated balance sheet, respectively. As of December 31, 2018 , the balance of the contingent liability related to probable future milestone payments under the License Agreement was $12.4 million , of which $0.9 million and $11.5 million were included in accrued liabilities and other non-current liabilities on the consolidated balance sheet, respectively. As of March 31, 2019 , the gross carrying amount of the indefinite-lived intangible asset was $14.9 million . During the three months ended March 31, 2019 , the Company noted no events or circumstances that indicate the carrying value of the licensed technology may no longer be recoverable and that an impairment loss may have occurred.

Goodwill

Goodwill	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	7. Goodwill The following table presents the changes in goodwill during the three months ended March 31, 2019 (in thousands): Total Company Balance as of December 31, 2018 $ 7,813 Foreign currency translation (154 ) Balance as of March 31, 2019 $ 7,659 Goodwill Impairment Review The Company reviews goodwill for impairment annually during the fourth quarter, on October 31st, or more frequently if events or circumstances indicate that an impairment loss may have occurred. During the three months ended March 31, 2019 , there were no events or changes in circumstances which triggered an impairment review .

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	8. Leases Adoption of ASC Topic 842, “Leases” The Company adopted the guidance under ASC 842 on January 1, 2019 using the modified retrospective transition approach. Therefore the comparative prior year information has not been adjusted and continues to be reported under ASC 840. The impact of the adoption of ASC 842 on the Company’s condensed consolidated balance sheet as of January 1, 2019 was as follows (in thousands): December 31, 2018 Adjustments due to the adoption of Topic 842 January 1, 2019 Assets Prepaid expenses and other current assets (1) 12,200 (424 ) 11,776 Total current assets 410,726 (424 ) 410,302 Operating lease right-of-use assets (1) — 43,277 43,277 Total assets $ 515,006 $ 42,853 $ 557,859 Liabilities and Stockholders’ Equity Current liabilities: Accrued liabilities (2) 57,886 (132 ) 57,754 Current operating lease liabilities (2) — 3,608 3,608 Total current liabilities 66,062 3,476 69,538 Deferred rent (2) 7,586 (7,586 ) — Non-current operating lease liabilities (2) — 46,963 46,963 Total liabilities 92,591 42,853 135,444 Total liabilities and stockholders’ equity $ 515,006 $ 42,853 $ 557,859 (1) Upon the adoption of ASC 842, prepaid rent is included in the operating lease right-of-use assets. (2) Upon the adoption of ASC 842, current and non-current deferred rent is included in the current and non-current operating lease liabilities. Lease Overview As of December 31, 2018 and March 31, 2019 , the Company's contracts that contained a lease consisted of real estate, equipment and vehicle leases. The Company leases real estate for office and warehouse space primarily under non-cancelable operating leases that expire at various dates through 2031 , subject to the Company’s option to renew certain leases for an additional five to fifteen years . The Company also leases other equipment and vehicles primarily under non-cancelable operating leases that expire at various dates through 2023 . As of December 31, 2018 and March 31, 2019 , the Company did not have material finance leases. The following table presents the components of the Company’s lease cost, lease term and discount rate during the three months ended March 31, 2019 (in thousands, expect years and percentages): Three Months Ended Operating lease cost $ 1,768 Variable lease cost 758 Total lease costs $ 2,526 Weighted Average Remaining Lease Term Operating leases 10.6 years Weighted Average Discount Rate Operating leases 6.2 % (1) Variable lease costs represent payments that are dependent on usage, a rate or index. Variable lease cost primarily relates to common area maintenance charges for its real estate leases as the Company elected not to separate non-lease components from lease components upon adoption of ASC 842. Prior to January 1, 2019, the Company recorded operating lease rent expense under ASC 840 on a straight-line basis over the non-cancellable lease term . Rent expense for the three months ended March 31, 2018 was $1.4 million . During the third quarter of 2018, the Company signed a fifteen year lease for a manufacturing facility in Roseville, California (the “Roseville Lease”) which has not yet commenced as of March 31, 2019 . The Roseville Lease is expected to commence upon substantial completion of lessor owned improvements to the building which the Company anticipates will be in 2020. The following table is a schedule, by years, of maturities of the Company's lease liabilities as of March 31, 2019 (in thousands): Lease Payments (1) Remainder of 2019 $ 5,000 Year ending December 31, 2020 6,586 Year ending December 31, 2021 5,887 Year ending December 31, 2022 5,801 Year ending December 31, 2023 5,787 Year ending December 31, 2024 5,849 Thereafter 33,929 Total undiscounted lease payments $ 68,839 Less imputed interest (19,081 ) Present value of lease liabilities $ 49,758 (1) The table above excludes the estimated future minimum lease payment for the Roseville Lease, due to the uncertainty around the timing of when the Roseville Lease will commence and payments will be due. The total estimated lease payments over the fifteen year lease term is approximately $40.9 million . The table also excludes lease payments that were not fixed at commencement or modification. The following table below shows the maturities of the Company’s operating lease liabilities previously disclosed under ASC 840 as of December 31, 2018 (in thousands): Lease Payments (1) Year Ending December 31: 2019 $ 6,575 2020 6,571 2021 5,809 2022 5,772 2023 5,735 Thereafter 40,194 Total future minimum lease payments $ 70,656 (1) The table above excludes the estimated future minimum lease payment for the Roseville Lease, due to the uncertainty around the timing of when the Roseville Lease will commence and payments will be due. Supplemental cash flow information related to leases during the three months ended March 31, 2019 are as follows (in thousands): Three Months Ended Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 1,623

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies 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, 2019 and December 31, 2018 , 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 shall 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 shall continue until the expiration of the last to expire patent that covers that licensed product or for the period of fifteen years following the first commercial sale of such licensed product, whichever is longer. The first commercial sale of covered products occurred in June 2007. 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. The first commercial sale of covered products occurred in April 2014. Unless terminated earlier, the royalty term for each applicable product shall continue for fifteen years following the first commercial sale of such patented product, or when the applicable patent covering such product has expired, whichever is sooner. In November 2013, the Company entered into an agreement that required the Company to pay, on a quarterly basis, a 3% royalty on the first $5.0 million in sales and a 1% royalty on sales thereafter of products covered under applicable patents. The agreement was terminated effective January 1, 2018. In April 2015, the Company entered into a royalty agreement that required the Company to pay a 2% royalty on sales of certain products covered by the agreement, on a quarterly basis, in exchange for certain trade secrets and processes which were used to develop such covered products. The Company began the first commercial sale of the covered products in July 2015. In the first quarter of 2018, the Company entered into a buyout agreement (the “Buyout Agreement”) in which future royalty payments under the royalty agreement were canceled in exchange for shares of the Company’s common stock with a fair value of $5.3 million . The Company recorded an intangible asset equal to the $5.3 million buyout amount which will be amortized into cost of sales over the period in which the Company receives future economic benefit . After determining that the pattern of future cash flows associated with this intangible asset could not be reliably estimated with a high level of precision, the Company concluded that the intangible asset will be amortized on a straight‑line basis over its estimated useful life. For more information refer to Note “ 10. Stockholders’ Equity .” Royalty expense included in cost of revenue for the three months ended March 31, 2019 and 2018 , was $1.1 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. Refer to Note “ 3. Investments and Fair Value of Financial Instruments ,” Note “ 5. Asset Acquisitions and Business Combinations ” and Note “ 6. Intangible Assets ” for more information on contingent liabilities recorded on the condensed consolidated balance sheet. 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 From time to time, the Company is subject to other claims and assessments in the ordinary course of business. The Company is not currently a party to any such 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
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stockholder's Equity	10. Stockholders’ Equity Common Stock In the first quarter of 2018, the Company issued 53,256 fully vested restricted stock units with a fair value of $5.3 million in connection with the Buyout Agreement, as discussed in Note “ 9. Commitments and Contingencies .” The Company recorded the $5.3 million fair value of the shares issued to additional-paid in capital on the condensed consolidated balance sheet upon the issuance of the awards, with the associated expense being amortized into cost of sales over the period in which the Company receives future economic benefit from the buyout. 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, 2019 is set forth below: Number of Shares Weighted-Average Exercise Price Balance at December 31, 2018 1,688,881 $ 18.91 Exercised (89,451 ) 11.97 Canceled/Forfeited (3,175 ) 21.94 Balance at March 31, 2019 1,596,255 19.29 Restricted Stock and Restricted Stock Units Activity of unvested restricted stock awards and restricted stock units under the Plans during the three months ended March 31, 2019 is set forth below: Number of Shares Weighted -Average Grant Date Fair Value Unvested at December 31, 2018 451,463 $ 57.29 Granted 63,113 146.80 Vested (51,147 ) 60.82 Canceled/Forfeited (1,350 ) 92.69 Unvested at March 31, 2019 462,079 69.02 As of March 31, 2019 , 449,313 restricted stock awards and restricted stock units are expected to vest. Stock-based Compensation The following table sets forth the stock-based compensation expense included in the Company’s condensed consolidated statements of operations for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 2018 Cost of revenue $ 291 $ 219 Research and development 524 368 Sales, general and administrative 4,280 3,567 Total $ 5,095 $ 4,154 As of March 31, 2019 , total unrecognized compensation cost was $25.8 million related to unvested share-based compensation arrangements which is expected to be recognized over a weighted average period of 2.5 years . The total stock-based compensation cost capitalized in inventory was $0.5 million and $0.4 million as of March 31, 2019 and December 31, 2018 , respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	11. Accumulated Other Comprehensive (Loss) Income Other comprehensive (loss) 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 (loss) income, these comprehensive income (loss) 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, 2019 and March 31, 2018 , 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 consolidated statements of comprehensive (loss) income (in thousands): Three Months Ended March 31, 2019 Three Months Ended March 31, 2018 Marketable Currency Translation Total Marketable Currency Translation Total Balance at beginning of the period $ (500 ) $ (1,442 ) $ (1,942 ) $ (235 ) $ 1,804 $ 1,569 Other comprehensive (loss) income before reclassifications: Unrealized gain (losses)— marketable investments 462 — 462 (386 ) — (386 ) Foreign currency translation (losses) gains — (1,098 ) (1,098 ) — 1,608 1,608 Income tax effect — benefit (expense) — — — 68 (222 ) (154 ) Net of tax 462 (1,098 ) (636 ) (318 ) 1,386 1,068 Amounts reclassified from accumulated other comprehensive income to earnings: Income tax effect — expenses — — — — — — Net of tax — — — — — — Net current-year other comprehensive (loss) income 462 (1,098 ) (636 ) (318 ) 1,386 1,068 Balance at end of the period $ (38 ) $ (2,540 ) $ (2,578 ) $ (553 ) $ 3,190 $ 2,637

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	12. 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. Jurisdictions with tax assets for which the Company believes a tax benefit cannot be realized are excluded from the computation of its annual effective tax rate. The Company’s provision for income taxes was $1.5 million for the three months ended March 31, 2019 , compared to a $1.9 million of tax benefit for the three months ended March 31, 2018 . The Company’s effective tax rate changed to 12.2% for the three months ended March 31, 2019 , compared to (43.0)% for the three months ended March 31, 2018 . The Company’s provision for (benefit from) income taxes for the three months ended March 31, 2019 and 2018 were primarily due to income taxes attributable to its worldwide profits offset by excess tax benefits from stock-based compensation attributable to the Company’s U.S. jurisdiction. The change in rate was primarily attributable to income taxes on higher worldwide profits combined with lower excess stock-based compensation tax benefits for the three months ended March 31, 2019, when compared to the three months ended March 31, 2018. The 2017 Tax Reform Act significantly revised the U.S. corporate income tax regime. In addition, the Securities and Exchange Commission issued Staff Accounting Bulletin 118 (“SAB 118”), which provided a measurement period, that should not extend beyond one year from the Tax Reform Act enactment date. In the period ended December 31, 2018, the Company completed its accounting for the tax effects of the Tax Reform Act under FASB ASC 740 “Income Taxes” based on authoritative guidance available to date. The Company will continue to evaluate the impact of further guidance from federal and state tax authorities on the financial statements and determine if any adjustments to the previously recorded tax effects of the Tax Reform Act under ASC 740 will be required. Significant domestic deferred tax assets (“DTAs”) were generated in recent years, primarily due to excess tax benefits from stock option exercises and vesting of restricted stock. The Company evaluates all available positive and negative evidence, objective and subjective in nature, in each reporting period to determine if sufficient taxable income will be generated to realize the benefits of its DTAs and, if not, a valuation allowance to reduce the DTAs is recorded. As of March 31, 2019 and 2018, the Company maintains a valuation allowance against its Federal Research and Development Tax Credit and California DTAs as the Company could not conclude at the required more-likely-than-not level of certainty, that the benefit of these tax attributes would be realized prior to expiration. As of March 31, 2019, the Company also maintains a valuation allowance against DTAs acquired from MVI which are subject to Separate Return Limitation Year (“SRLY”) rules that limit the utilization of the pre-acquisition tax attributes to offset future taxable income solely generated by MVI. The Company maintains that all foreign earnings, with the exception of a portion of the earnings of its German subsidiary, are permanently reinvested outside the United States and therefore deferred taxes attributable to such are not provided for in the Company’s financial statements as of March 31, 2019. The Company will repatriate foreign earnings only to the extent doing so will not result in any material U.S. tax consequences. Thus, deferred taxes on any potential future repatriation of a portion of the earnings of its German subsidiary were not reflected in the Company’s financial statements as of March 31, 2019.

Net Income per Share

Net Income per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Net Income per Share	13. Net Income Attributable to Penumbra, Inc. Per Share The Company’s basic net income attributable to Penumbra, Inc. per share is calculated by dividing the net income attributable to Penumbra, Inc. by the weighted average number of shares of common stock outstanding for the period. The diluted net 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, restricted stock units and stock sold through the Company’s employee stock purchase plan are considered common stock equivalents. A reconciliation of the numerator and denominator used in the calculation of the basic and diluted net income per share for the three months ended March 31, 2019 and 2018 is as follows (in thousands, except share and per share amounts): Three Months Ended March 31, 2019 2018 Numerator: Net income attributable to Penumbra, Inc. $ 10,698 $ 5,491 Denominator: Weighted average shares used to compute net income: Basic 34,507,279 33,846,142 Effect of dilutive securities from stock-based benefit plans, as calculated using treasury stock method 1,705,885 2,070,909 Diluted 36,213,164 35,917,051 Net income attributable to Penumbra, Inc. per share from: Basic $ 0.31 $ 0.16 Diluted $ 0.30 $ 0.15 Outstanding common stock equivalents of 57 thousand and 24 thousand shares for the three months ended March 31, 2019 and 2018 , respectively, were excluded from the computation of diluted net income attributable to Penumbra, Inc. per share because their effect would have been anti-dilutive.

Revenues

Revenues	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenues	14. Revenues Revenue Recognition Revenue is recognized in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. All revenue recognized in the income statement is considered to be revenue from contracts with customers. The following table presents the Company’s revenues disaggregated by geography , based on the destination to which the Company ships its products, for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 2018 United States $ 82,511 $ 65,801 Japan 9,522 10,682 Other International 36,406 26,218 Total $ 128,439 $ 102,701 The following table presents the Company’s revenues disaggregated by product category, for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 2018 Neuro $ 81,471 $ 71,433 Vascular 46,968 31,268 Total $ 128,439 $ 102,701 Performance Obligations Delivery of products - The Company’s contracts with customers typically contain a single performance obligation, delivery of Penumbra products. Satisfaction of that performance obligation occurs when control of the promised goods transfers to the customer, which is generally upon shipment for non-consignment sale agreements and upon utilization for consignment sale agreements. Payment terms - The Company’s payment terms vary by the type and location of our customer. The timing between fulfillment of performance obligations and when payment is due is not significant and does not give rise to financing transactions. The Company did not have any contracts with significant financing components as of March 31, 2019 . Product returns - The Company may allow customers to return products purchased at the Company’s discretion. The Company estimates the amount of its product sales that may be returned by its customers and records this estimate as a reduction of revenue in the period the related product revenue is recognized. The Company currently estimates product return liabilities using its own historic sales information, trends, industry data, and other relevant data points. Warranties - The Company offers its standard warranty to all customers and it is not available for sale on a standalone basis. The Company’s standard warranty represents its guarantee that its products function as intended, are free from defects, and comply with agreed-upon specifications and quality standards. This assurance does not constitute a service and is not a separate performance obligation. Transaction Price Revenue is recorded at the net sales price, which includes estimates of variable consideration such as product returns utilizing historical return rates, rebates, discounts, and other adjustments to net revenue. To the extent the transaction price includes variable consideration, the Company estimates the amount of variable consideration that should be included in the transaction price. When determining if variable consideration should be constrained, management considers whether there are factors that could result in a significant reversal of revenue and the likelihood of a potential reversal. Variable consideration is included in revenue only to the extent that it is probable that a significant reversal of the revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. These estimates are re-assessed each reporting period as required. During the three months ended March 31, 2019 , the Company made no changes in estimates for variable consideration. When the Company performs shipping and handling activities after control of goods is transferred to the customer, they are considered as fulfillment activities, and costs are accrued for when the related revenue is recognized. Taxes collected from customers relating to product sales and remitted to governmental authorities are excluded from revenues.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation and Consolidation The accompanying condensed consolidated balance sheet as of March 31, 2019 , the condensed consolidated statements of operations for the three months ended March 31, 2019 and 2018 , the condensed consolidated statements of comprehensive income for the three months ended March 31, 2019 and 2018 , the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2019 and 2018 , and the condensed consolidated statements of cash flows for the three months ended March 31, 2019 and 2018 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 U.S. 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, 2018 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, 2019 , the results of its operations for the three months ended March 31, 2019 and 2018 , the changes in stockholders’ equity for the three months ended March 31, 2019 and 2018 , and the cash flows for the three months ended March 31, 2019 and 2018 . The results for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 or for any other future annual or interim period. 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, 2018 , 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, 2019 , 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, 2018 , other than changes to the Company’s leasing policy described below in connection with the adoption of the guidance under Accounting Standards Codification (“ASC”) 842.
Consolidation	The condensed consolidated financial statements include the accounts of the Company, its wholly-owned subsidiaries and its majority-owned subsidiary. The portion of equity not attributable to the Company is considered non-controlling interest and is classified separately in the condensed consolidated financial statements. Any subsequent changes in the Company’s ownership interest while the Company retains its controlling interest in its majority-owned subsidiary will be accounted for as equity transactions. All intercompany balances and transactions have been eliminated in consolidation.
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, the amount of variable consideration included in the transaction price, warranty reserve, valuation of inventories, useful lives of property and equipment, operating lease right-of-use (“ROU”) assets and liabilities, income taxes, contingent consideration and other 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.
Recent Accounting Guidance	Recent Accounting Guidance Recently Issued Accounting Standards In June 2016, the Financial Accounting Standards Board (“ 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. In April 2019, the FASB issued ASU No. 2019-04 which provides additional clarification and address stakeholders’ specific issues about certain aspects of the amendments in the previously issued ASU No. 2016-13. 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 August 2018, the FASB issued ASU 2018-13, Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement . The primary focus of the standard is to improve the effectiveness of the disclosure requirements for fair value measurements. The standard is effective for fiscal years and interim periods beginning after December 15, 2019. An entity is permitted to early adopt the removed or modified disclosures upon the issuance of the standard and may delay adoption of the additional disclosures until their effective date. The Company is currently evaluating the impact of adopting this standard.
Leases	Leases The Company adopted the guidance under ASC 842 on January 1, 2019 using the modified retrospective transition approach. There was no cumulative-effect adjustment recorded to retained earnings upon adoption. Under ASC 842, the Company determines if an arrangement is a lease at inception. In addition, the Company determines whether leases meet the classification criteria of a finance or operating lease at the lease commencement date considering: (1) whether the lease transfers ownership of the underlying asset to the lessee at the end of the lease term, (2) whether the lease contains a bargain purchase option, (3) whether the lease term is for a major part of the remaining economic life of the underlying asset, (4) whether the present value of the sum of the lease payments and residual value guaranteed by the lessee equals or exceeds substantially all of the fair value of the underlying asset, and (5) whether the underlying asset is of such a specialized nature that it is expected to have no alternative use to the lessor at the end of the lease term. As of March 31, 2019, the Company's contracts that contained a lease consisted of real estate, equipment and vehicle leases. As of the date of adoption of ASC 842 and March 31, 2019, the Company did not have material finance leases. Operating leases are included in operating lease right-of-use assets, current operating lease liabilities, and non-current operating lease liabilities in our condensed consolidated balance sheet. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the present value of lease payments, the Company uses its incremental borrowing rate based on the information available at the lease commencement date if the rate implicit in the lease is not readily determinable. The determination of the Company’s incremental borrowing rate requires management judgment including, the development of a synthetic credit rating and cost of debt as the Company currently does not carry any debt. The operating lease ROU assets also include adjustments for prepayments, accrued lease payments and exclude lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise such options. Operating lease cost is recognized on a straight-line basis over the expected lease term. Lease agreements entered into after the adoption of ASC 842 that include lease and non-lease components are accounted for as a single lease component. Lease agreements with a noncancelable term of less than 12 months are not recorded on the Company’s condensed consolidated balance sheet. For more information about the impact of adoption and disclosures on the Company’s leases, refer to Note “ 8. Leases .”
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 devices, and operates as one operating segment. The Company’s chief operating decision-maker, its Chief Executive Officer, reviews its consolidated operating results for the purpose of allocating resources and evaluating financial performance.
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	Recently Adopted Accounting Standards On January 1, 2019, the Company adopted Accounting Standard Update (“ASU”) No. 2016-02 , Leases (Topic 842) , and its associated amendments using the modified retrospective transition approach by applying the new standard to all leases existing at the date of initial application and not restating comparative periods. There was no cumulative-effect adjustment recorded to retained earnings upon adoption. Under the standard, a lessee is required to recognize a lease liability and ROU asset for all leases. The new guidance also modified the classification criteria 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 continues to depend primarily on its classification. The Company elected the package of practical expedients permitted under the transition guidance, which allowed the Company to carryforward its historical lease classification, its assessment on whether a contract was or contains a lease, and its initial direct costs for any leases that existed prior to January 1, 2019. In addition, the Company elected the following transitional practical expedients: (1) the short-term lease exception and (2) to not separate its non-lease components for its real estate, vehicle and equipment leases. The impact of adoption and additional disclosures required by the ASU have been included in “Significant Accounting Policies - Leases” below and in Note “ 8. Leases .”

Investments and Fair Value of_2

Investments and Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of Marketable Investments	Marketable Investments The Company’s marketable investments have been classified and accounted for as available-for-sale. The following table presents the Company’s marketable investments as of March 31, 2019 and December 31, 2018 (in thousands): March 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 1,500 $ — $ — $ 1,500 U.S. treasury 2,400 — (9 ) 2,391 U.S. agency and government sponsored securities 7,708 21 (14 ) 7,715 U.S. states and municipalities 3,631 1 — 3,632 Corporate bonds 84,039 94 (130 ) 84,003 Total $ 99,278 $ 116 $ (153 ) $ 99,241 December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Commercial paper $ 13,701 $ — $ (3 ) $ 13,698 U.S. treasury 6,400 — (22 ) 6,378 U.S. agency and government sponsored securities 7,699 18 (27 ) 7,690 U.S. states and municipalities 5,134 — (12 ) 5,122 Corporate bonds 100,606 14 (469 ) 100,151 Total $ 133,540 $ 32 $ (533 ) $ 133,039
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 or for twelve months or more as of March 31, 2019 and December 31, 2018 (in thousands): March 31, 2019 Less than 12 months 12 months or more Total Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses U.S. treasury $ — $ — $ 2,391 $ (9 ) $ 2,391 $ (9 ) U.S. agency and government sponsored securities — — 4,211 (14 ) 4,211 (14 ) Corporate bonds 8,307 (6 ) 31,435 (124 ) 39,742 (130 ) Total $ 8,307 $ (6 ) $ 38,037 $ (147 ) $ 46,344 $ (153 ) December 31, 2018 Less than 12 months 12 months or more Total Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Commercial paper $ 12,208 $ (3 ) $ — $ — $ 12,208 $ (3 ) U.S. treasury — — 6,378 (22 ) 6,378 (22 ) U.S. agency and government sponsored securities 1,436 (5 ) 2,759 (22 ) 4,195 (27 ) U.S. states and municipalities 1,529 (5 ) 3,593 (7 ) 5,122 (12 ) Corporate bonds 58,961 (176 ) 33,215 (293 ) 92,176 (469 ) Total $ 74,134 $ (189 ) $ 45,945 $ (344 ) $ 120,079 $ (533 )
Schedule of Contractual Maturities of Marketable Investments	The following table presents the contractual maturities of the Company’s marketable investments as of March 31, 2019 and December 31, 2018 (in thousands): March 31, 2019 December 31, 2018 Fair Value Fair Value Due in less than one year $ 53,205 $ 83,391 Due in one to five years 46,036 49,648 Total $ 99,241 $ 133,039
Schedule of Fair Value of Assets and Liabilities	The following tables set forth the Company’s financial assets measured at fair value by level within the fair value hierarchy as of March 31, 2019 and December 31, 2018 (in thousands): As of March 31, 2019 Level 1 Level 2 Level 3 Fair Value Financial Assets Cash equivalents: Money market funds $ 44,331 $ — $ — $ 44,331 Marketable investments: Commercial paper — 1,500 — 1,500 U.S. treasury 2,391 — — 2,391 U.S. agency and government sponsored securities — 7,715 — 7,715 U.S. states and municipalities — 3,632 — 3,632 Corporate bonds — 84,003 — 84,003 Total $ 46,722 $ 96,850 $ — $ 143,572 Financial Liabilities: Contingent consideration obligations (1) $ — $ — $ 1,248 $ 1,248 Total $ — $ — $ 1,248 $ 1,248 (1) More information on the contingent consideration obligations and the changes in fair value are presented below. As of December 31, 2018 Level 1 Level 2 Level 3 Fair Value Financial Assets Cash equivalents: Commercial paper $ — $ 10,967 $ — $ 10,967 Money market funds 12,087 — — 12,087 Marketable investments: Commercial paper — 13,698 — 13,698 U.S. treasury 6,378 — — 6,378 U.S. agency and government sponsored securities — 7,690 — 7,690 U.S. states and municipalities — 5,122 — 5,122 Corporate bonds — 100,151 — 100,151 Total $ 18,465 $ 137,628 $ — $ 156,093 Financial Liabilities: Contingent consideration obligations (1) $ — $ — $ 2,571 $ 2,571 Total $ — $ — $ 2,571 $ 2,571 (1) More information on the contingent consideration obligations and the changes in fair value are presented below.
Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]	The following table presents quantitative information about certain unobservable inputs used in the Level 3 fair value measurement of the Company’s contingent consideration liability, other than the forecasted revenues during the earn-out milestone period: Fair Value at March 31, 2019 (in thousands) Valuation Method Unobservable Inputs Input (range where applicable) Crossmed: Revenue-based milestones $ 1,248 Monte Carlo Simulation Earn-out period over which revenue-based milestone payments are made 2019 Risk-adjusted discount rate 15% Revenue volatilities for each type of revenue-based milestone 5.1% and 18.4%
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	The following tables summarize the changes in fair value of the contingent consideration obligation for the three months ended March 31, 2019 and March 31, 2018 (in thousands): Fair Value of Contingent Consideration Balance at December 31, 2018 $ 2,571 Payments of contingent consideration liabilities (1,296 ) Changes in fair value — Foreign currency remeasurement (27 ) Balance at March 31, 2019 $ 1,248 Fair Value of Contingent Consideration Balance at December 31, 2017 $ 4,675 Payments of contingent consideration liabilities (3,017 ) Changes in fair value 442 Foreign currency remeasurement 133 Balance at March 31, 2018 $ 2,233

Balance Sheet Components Balanc

Balance Sheet Components Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Inventories	The following table shows the components of inventories as of March 31, 2019 and December 31, 2018 (in thousands): March 31, December 31, Raw materials $ 18,968 $ 18,829 Work in process 12,502 10,630 Finished goods 90,221 86,282 Inventories $ 121,691 $ 115,741
Schedule of Accrued Liabilities	The following table shows the components of accrued liabilities as of March 31, 2019 and December 31, 2018 (in thousands): March 31, December 31, Payroll and employee-related cost $ 31,940 $ 33,838 Accrued expenses 5,094 4,088 Sales return provision 2,269 2,986 Product warranty 2,077 1,875 Contingent consideration & other acquisition-related costs (1) 4,611 4,439 Other accrued liabilities 12,041 10,660 Total accrued liabilities $ 58,032 $ 57,886 (1) Amount consists of the current portion of contingent liabilities related to (1) the cash milestone payments and working capital adjustment liabilities for the 2017 acquisition of Crossmed and (2) an anti-dilution provision for the 2018 asset acquisition of MVI. Refer to Note “ 5. Asset Acquisitions and Business Combinations ” for more information on the acquisition of Crossmed and asset acquisition of MVI.
Schedule of Estimated Product Warranty Accrual	The following table shows the changes in the Company’s estimated product warranty accrual, included in accrued liabilities, as of March 31, 2019 and December 31, 2018 (in thousands): March 31, December 31, Balance at the beginning of the period $ 1,875 $ 1,088 Accruals of warranties issued 355 1,336 Settlements of warranty claims (153 ) (549 ) Balance at the end of the period $ 2,077 $ 1,875
Schedule of Other Non-Current Liabilities	The following table shows the components of other non-current liabilities as of March 31, 2019 and December 31, 2018 (in thousands): March 31, December 31, Deferred tax liabilities $ 3,972 $ 4,171 Licensing-related cost (1) 11,463 11,506 Asset acquisition-related costs (2) 1,000 2,500 Other non-current liabilities 209 766 Total other non-current liabilities $ 16,644 $ 18,943 (1) Amount relates to the non-current liability recorded for probable future milestone payments to be made under the licensing agreement described in Note “ 6. Intangible Assets .” Refer therein for more information. (2) Asset acquisition-related costs represents the non-current portion of the probable contingent liability related to an anti-dilution provision for the 2018 asset acquisition of MVI.

Intangible Assets Intangible As

Intangible Assets Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2019
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Schedule of indefinite-lived intangible assets	The following tables present details of the Company’s acquired finite-lived and indefinite-lived intangible assets, as of March 31, 2019 and December 31, 2018 (in thousands, except weighted-average amortization period): March 31, 2019 Weighted-Average Amortization Period Gross Carrying Amount Accumulated Amortization Net Customer relationships 15.0 years $ 6,688 $ (781 ) $ 5,907 Trade secrets and processes 20.0 years 5,256 (329 ) 4,927 Other 5.0 years 1,725 (603 ) 1,122 Total intangible assets subject to amortization 16.1 years $ 13,669 $ (1,713 ) $ 11,956 Intangible assets related to licensed technology 14,857 — 14,857 Total intangible assets $ 28,526 $ (1,713 ) $ 26,813 December 31, 2018 Weighted-Average Amortization Period Gross Carrying Amount Accumulated Amortization Net Customer relationships 15.0 years $ 6,823 $ (681 ) $ 6,142 Trade secrets and processes 20.0 years 5,256 (263 ) 4,993 Other 5.0 years 1,759 (528 ) 1,231 Total intangible assets subject to amortization 16.0 years $ 13,838 $ (1,472 ) $ 12,366 Intangible assets related to licensed technology 14,879 — 14,879 Total intangible assets $ 28,717 $ (1,472 ) $ 27,245
Finite-lived Intangible Assets Amortization Expense	The following table presents the amortization expense recorded related to the Company’s finite-lived intangible assets for the three months ended March 31, 2019 and March 31, 2018 (in thousands): Three Months Ended March 31, 2019 2018 Cost of revenue $ 66 $ 31 Sales, general and administrative 200 216 Total $ 266 $ 247

Goodwill Goodwill (Tables)

Goodwill Goodwill (Tables)	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill	The following table presents the changes in goodwill during the three months ended March 31, 2019 (in thousands): Total Company Balance as of December 31, 2018 $ 7,813 Foreign currency translation (154 ) Balance as of March 31, 2019 $ 7,659

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The impact of the adoption of ASC 842 on the Company’s condensed consolidated balance sheet as of January 1, 2019 was as follows (in thousands): December 31, 2018 Adjustments due to the adoption of Topic 842 January 1, 2019 Assets Prepaid expenses and other current assets (1) 12,200 (424 ) 11,776 Total current assets 410,726 (424 ) 410,302 Operating lease right-of-use assets (1) — 43,277 43,277 Total assets $ 515,006 $ 42,853 $ 557,859 Liabilities and Stockholders’ Equity Current liabilities: Accrued liabilities (2) 57,886 (132 ) 57,754 Current operating lease liabilities (2) — 3,608 3,608 Total current liabilities 66,062 3,476 69,538 Deferred rent (2) 7,586 (7,586 ) — Non-current operating lease liabilities (2) — 46,963 46,963 Total liabilities 92,591 42,853 135,444 Total liabilities and stockholders’ equity $ 515,006 $ 42,853 $ 557,859 (1) Upon the adoption of ASC 842, prepaid rent is included in the operating lease right-of-use assets. (2) Upon the adoption of ASC 842, current and non-current deferred rent is included in the current and non-current operating lease liabilities.
Lease, Cost	The following table presents the components of the Company’s lease cost, lease term and discount rate during the three months ended March 31, 2019 (in thousands, expect years and percentages): Three Months Ended Operating lease cost $ 1,768 Variable lease cost 758 Total lease costs $ 2,526 Weighted Average Remaining Lease Term Operating leases 10.6 years Weighted Average Discount Rate Operating leases 6.2 %
Lessee, Operating Lease, Liability, Maturity	The following table is a schedule, by years, of maturities of the Company's lease liabilities as of March 31, 2019 (in thousands): Lease Payments (1) Remainder of 2019 $ 5,000 Year ending December 31, 2020 6,586 Year ending December 31, 2021 5,887 Year ending December 31, 2022 5,801 Year ending December 31, 2023 5,787 Year ending December 31, 2024 5,849 Thereafter 33,929 Total undiscounted lease payments $ 68,839 Less imputed interest (19,081 ) Present value of lease liabilities $ 49,758 (1) The table above excludes the estimated future minimum lease payment for the Roseville Lease, due to the uncertainty around the timing of when the Roseville Lease will commence and payments will be due. The total estimated lease payments over the fifteen year lease term is approximately $40.9 million . The table also excludes lease payments that were not fixed at commencement or modification.
Schedule of Future Minimum Rental Payments for Operating Leases	The following table below shows the maturities of the Company’s operating lease liabilities previously disclosed under ASC 840 as of December 31, 2018 (in thousands): Lease Payments (1) Year Ending December 31: 2019 $ 6,575 2020 6,571 2021 5,809 2022 5,772 2023 5,735 Thereafter 40,194 Total future minimum lease payments $ 70,656 (1) The table above excludes the estimated future minimum lease payment for the Roseville Lease, due to the uncertainty around the timing of when the Roseville Lease will commence and payments will be due.
Schedule of Cash Flow, Supplemental Disclosures	Supplemental cash flow information related to leases during the three months ended March 31, 2019 are as follows (in thousands): Three Months Ended Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 1,623

Stockholder's Equity (Tables)

Stockholder's Equity (Tables)	3 Months Ended
	Mar. 31, 2019
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, 2019 is set forth below: Number of Shares Weighted-Average Exercise Price Balance at December 31, 2018 1,688,881 $ 18.91 Exercised (89,451 ) 11.97 Canceled/Forfeited (3,175 ) 21.94 Balance at March 31, 2019 1,596,255 19.29
Summary of Unvested Restricted Stock and Restricted Stock Unit Activity	Activity of unvested restricted stock awards and restricted stock units under the Plans during the three months ended March 31, 2019 is set forth below: Number of Shares Weighted -Average Grant Date Fair Value Unvested at December 31, 2018 451,463 $ 57.29 Granted 63,113 146.80 Vested (51,147 ) 60.82 Canceled/Forfeited (1,350 ) 92.69 Unvested at March 31, 2019 462,079 69.02
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 for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 2018 Cost of revenue $ 291 $ 219 Research and development 524 368 Sales, general and administrative 4,280 3,567 Total $ 5,095 $ 4,154

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) AOCI (Tables)	3 Months Ended
	Mar. 31, 2019
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, 2019 and March 31, 2018 , 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 consolidated statements of comprehensive (loss) income (in thousands): Three Months Ended March 31, 2019 Three Months Ended March 31, 2018 Marketable Currency Translation Total Marketable Currency Translation Total Balance at beginning of the period $ (500 ) $ (1,442 ) $ (1,942 ) $ (235 ) $ 1,804 $ 1,569 Other comprehensive (loss) income before reclassifications: Unrealized gain (losses)— marketable investments 462 — 462 (386 ) — (386 ) Foreign currency translation (losses) gains — (1,098 ) (1,098 ) — 1,608 1,608 Income tax effect — benefit (expense) — — — 68 (222 ) (154 ) Net of tax 462 (1,098 ) (636 ) (318 ) 1,386 1,068 Amounts reclassified from accumulated other comprehensive income to earnings: Income tax effect — expenses — — — — — — Net of tax — — — — — — Net current-year other comprehensive (loss) income 462 (1,098 ) (636 ) (318 ) 1,386 1,068 Balance at end of the period $ (38 ) $ (2,540 ) $ (2,578 ) $ (553 ) $ 3,190 $ 2,637

Net Income per Share Net Income

Net Income per Share Net Income Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
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 income per share for the three months ended March 31, 2019 and 2018 is as follows (in thousands, except share and per share amounts): Three Months Ended March 31, 2019 2018 Numerator: Net income attributable to Penumbra, Inc. $ 10,698 $ 5,491 Denominator: Weighted average shares used to compute net income: Basic 34,507,279 33,846,142 Effect of dilutive securities from stock-based benefit plans, as calculated using treasury stock method 1,705,885 2,070,909 Diluted 36,213,164 35,917,051 Net income attributable to Penumbra, Inc. per share from: Basic $ 0.31 $ 0.16 Diluted $ 0.30 $ 0.15

Revenues Revenues (Tables)

Revenues Revenues (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table presents the Company’s revenues disaggregated by geography , based on the destination to which the Company ships its products, for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 2018 United States $ 82,511 $ 65,801 Japan 9,522 10,682 Other International 36,406 26,218 Total $ 128,439 $ 102,701 The following table presents the Company’s revenues disaggregated by product category, for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 2018 Neuro $ 81,471 $ 71,433 Vascular 46,968 31,268 Total $ 128,439 $ 102,701

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Disclosures (Details)	3 Months Ended
	Mar. 31, 2019USD ($)segmentactivity	Jan. 01, 2018USD ($)
Accounting Policies [Abstract]
Leases	Leases The Company adopted the guidance under ASC 842 on January 1, 2019 using the modified retrospective transition approach. There was no cumulative-effect adjustment recorded to retained earnings upon adoption. Under ASC 842, the Company determines if an arrangement is a lease at inception. In addition, the Company determines whether leases meet the classification criteria of a finance or operating lease at the lease commencement date considering: (1) whether the lease transfers ownership of the underlying asset to the lessee at the end of the lease term, (2) whether the lease contains a bargain purchase option, (3) whether the lease term is for a major part of the remaining economic life of the underlying asset, (4) whether the present value of the sum of the lease payments and residual value guaranteed by the lessee equals or exceeds substantially all of the fair value of the underlying asset, and (5) whether the underlying asset is of such a specialized nature that it is expected to have no alternative use to the lessor at the end of the lease term. As of March 31, 2019, the Company's contracts that contained a lease consisted of real estate, equipment and vehicle leases. As of the date of adoption of ASC 842 and March 31, 2019, the Company did not have material finance leases. Operating leases are included in operating lease right-of-use assets, current operating lease liabilities, and non-current operating lease liabilities in our condensed consolidated balance sheet. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the present value of lease payments, the Company uses its incremental borrowing rate based on the information available at the lease commencement date if the rate implicit in the lease is not readily determinable. The determination of the Company’s incremental borrowing rate requires management judgment including, the development of a synthetic credit rating and cost of debt as the Company currently does not carry any debt. The operating lease ROU assets also include adjustments for prepayments, accrued lease payments and exclude lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise such options. Operating lease cost is recognized on a straight-line basis over the expected lease term. Lease agreements entered into after the adoption of ASC 842 that include lease and non-lease components are accounted for as a single lease component. Lease agreements with a noncancelable term of less than 12 months are not recorded on the Company’s condensed consolidated balance sheet. For more information about the impact of adoption and disclosures on the Company’s leases, refer to Note “ 8. Leases .”
Number of business activities | activity	1
Number of Operating Segments | segment	1
Cumulative effect adjustments | $	$ 0	$ 464,000

Investments and Fair Value of_3

Investments and Fair Value of Financial Instruments - Gains and Losses of Marketable Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 99,278	$ 133,540
Gross Unrealized Gains	116	32
Gross Unrealized Losses	(153)	(533)
Fair Value	99,241	133,039
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,500	13,701
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(3)
Fair Value	1,500	13,698
U.S. treasury
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,400	6,400
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(9)	(22)
Fair Value	2,391	6,378
U.S. agency and government sponsored securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,708	7,699
Gross Unrealized Gains	21	18
Gross Unrealized Losses	(14)	(27)
Fair Value	7,715	7,690
U.S. states and municipalities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,631	5,134
Gross Unrealized Gains	1	0
Gross Unrealized Losses	0	(12)
Fair Value	3,632	5,122
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	84,039	100,606
Gross Unrealized Gains	94	14
Gross Unrealized Losses	(130)	(469)
Fair Value	$ 84,003	$ 100,151

Investments and Fair Value of_4

Investments and Fair Value of Financial Instruments - Marketable Securities in an Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Less than 12 months: Fair Value	$ 8,307	$ 74,134
Less than 12 months: Gross Unrealized Losses	(6)	(189)
12 Months of more: Fair Value	38,037	45,945
12 months or more: Gross Unrealized Losses	(147)	(344)
Total: Fair Value	46,344	120,079
Total: Gross Unrealized Losses	(153)	(533)
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Less than 12 months: Fair Value		12,208
Less than 12 months: Gross Unrealized Losses		(3)
12 Months of more: Fair Value		0
12 months or more: Gross Unrealized Losses		0
Total: Fair Value		12,208
Total: Gross Unrealized Losses		(3)
U.S. treasury
Debt Securities, Available-for-sale [Line Items]
Less than 12 months: Fair Value	0	0
Less than 12 months: Gross Unrealized Losses	0	0
12 Months of more: Fair Value	2,391	6,378
12 months or more: Gross Unrealized Losses	(9)	(22)
Total: Fair Value	2,391	6,378
Total: Gross Unrealized Losses	(9)	(22)
U.S. agency and government sponsored securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months: Fair Value	0	1,436
Less than 12 months: Gross Unrealized Losses	0	(5)
12 Months of more: Fair Value	4,211	2,759
12 months or more: Gross Unrealized Losses	(14)	(22)
Total: Fair Value	4,211	4,195
Total: Gross Unrealized Losses	(14)	(27)
U.S. states and municipalities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months: Fair Value		1,529
Less than 12 months: Gross Unrealized Losses		(5)
12 Months of more: Fair Value		3,593
12 months or more: Gross Unrealized Losses		(7)
Total: Fair Value		5,122
Total: Gross Unrealized Losses		(12)
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Less than 12 months: Fair Value	8,307	58,961
Less than 12 months: Gross Unrealized Losses	(6)	(176)
12 Months of more: Fair Value	31,435	33,215
12 months or more: Gross Unrealized Losses	(124)	(293)
Total: Fair Value	39,742	92,176
Total: Gross Unrealized Losses	$ (130)	$ (469)

Investments and Fair Value of_5

Investments and Fair Value of Financial Instruments - Contractual Maturities of Marketable Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Due in less than one year	$ 53,205	$ 83,391
Due in one to five years	46,036	49,648
Total	$ 99,241	$ 133,039

Investments and Fair Value of_6

Investments and Fair Value of Financial Instruments - Financial Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Recurring
Financial Assets
Total	$ 143,572	$ 156,093
Financial Liabilities Fair Value Disclosure	1,248	2,571
Recurring | Commercial paper
Financial Assets
Marketable investments	1,500	13,698
Recurring | U.S. treasury
Financial Assets
Marketable investments	2,391	6,378
Recurring | U.S. agency and government sponsored securities
Financial Assets
Marketable investments	7,715	7,690
Recurring | U.S. states and municipalities
Financial Assets
Marketable investments	3,632	5,122
Recurring | Corporate bonds
Financial Assets
Marketable investments	84,003	100,151
Recurring | Commercial paper
Financial Assets
Cash equivalents		10,967
Recurring | Money market funds
Financial Assets
Cash equivalents	44,331	12,087
Recurring | Level 1
Financial Assets
Total	46,722	18,465
Financial Liabilities Fair Value Disclosure	0	0
Recurring | Level 1 | Commercial paper
Financial Assets
Marketable investments	0	0
Recurring | Level 1 | U.S. treasury
Financial Assets
Marketable investments	2,391	6,378
Recurring | Level 1 | U.S. agency and government sponsored securities
Financial Assets
Marketable investments	0	0
Recurring | Level 1 | U.S. states and municipalities
Financial Assets
Marketable investments	0	0
Recurring | Level 1 | Corporate bonds
Financial Assets
Marketable investments	0	0
Recurring | Level 1 | Commercial paper
Financial Assets
Cash equivalents		0
Recurring | Level 1 | Money market funds
Financial Assets
Cash equivalents	44,331	12,087
Recurring | Level 2
Financial Assets
Total	96,850	137,628
Financial Liabilities Fair Value Disclosure	0	0
Recurring | Level 2 | Commercial paper
Financial Assets
Marketable investments	1,500	13,698
Recurring | Level 2 | U.S. treasury
Financial Assets
Marketable investments	0	0
Recurring | Level 2 | U.S. agency and government sponsored securities
Financial Assets
Marketable investments	7,715	7,690
Recurring | Level 2 | U.S. states and municipalities
Financial Assets
Marketable investments	3,632	5,122
Recurring | Level 2 | Corporate bonds
Financial Assets
Marketable investments	84,003	100,151
Recurring | Level 2 | Commercial paper
Financial Assets
Cash equivalents		10,967
Recurring | Level 2 | Money market funds
Financial Assets
Cash equivalents	0	0
Recurring | Level 3
Financial Assets
Total	0	0
Financial Liabilities Fair Value Disclosure	1,248	2,571
Recurring | Level 3 | Commercial paper
Financial Assets
Marketable investments	0	0
Recurring | Level 3 | U.S. treasury
Financial Assets
Marketable investments	0	0
Recurring | Level 3 | U.S. agency and government sponsored securities
Financial Assets
Marketable investments	0	0
Recurring | Level 3 | U.S. states and municipalities
Financial Assets
Marketable investments	0	0
Recurring | Level 3 | Corporate bonds
Financial Assets
Marketable investments	0	0
Recurring | Level 3 | Commercial paper
Financial Assets
Cash equivalents		0
Recurring | Level 3 | Money market funds
Financial Assets
Cash equivalents	0	0
Contingent Consideration Liability | Recurring
Financial Assets
Financial Liabilities Fair Value Disclosure	1,248	2,571
Contingent Consideration Liability | Recurring | Level 1
Financial Assets
Financial Liabilities Fair Value Disclosure	0	0
Contingent Consideration Liability | Recurring | Level 2
Financial Assets
Financial Liabilities Fair Value Disclosure	0	0
Contingent Consideration Liability | Recurring | Level 3
Financial Assets
Financial Liabilities Fair Value Disclosure	1,248	2,571
Fair Value of Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	1,248		$ 2,233
Monte Carlo Simulation | Fair Value of Contingent Consideration | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	$ 1,248	$ 2,571		$ 4,675

Investments and Fair Value of_7

Investments and Fair Value of Financial Instruments - Quantitative Information On Unobservable Inputs (Details) - Monte Carlo Simulation - Level 3	3 Months Ended
	Mar. 31, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Inputs, Risk-Adjusted Discount Rate	15.00%
Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Input, Revenue Volatility	5.10%
Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Input, Revenue Volatility	18.40%

Investments and Fair Value of_8

Investments and Fair Value of Financial Instruments - Contingent Consideration (Details) - Fair Value of Contingent Consideration - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Payments of contingent consideration liabilities	$ (1,296)	$ (3,017)
March 31, 2019	1,248	2,233
Monte Carlo Simulation | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
December 31, 2018	2,571	4,675
March 31, 2019	1,248
Sales, general and administrative
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Changes in fair value	0	442
Other Expense [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Foreign currency remeasurement	$ (27)	$ 133

Balance Sheet Components - Inve

Balance Sheet Components - Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials	$ 18,968	$ 18,829
Work in process	12,502	10,630
Finished goods	90,221	86,282
Inventories	$ 121,691	$ 115,741

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Payroll and employee-related cost	$ 31,940		$ 33,838
Accrued expenses	5,094		4,088
Sales return provision	2,269		2,986
Product warranty	2,077		1,875
Contingent consideration & other acquisition-related costs(1)	4,611		4,439
Other accrued liabilities	12,041		10,660
Total accrued liabilities	$ 58,032	$ 57,754	$ 57,886

Balance Sheet Components - Prod

Balance Sheet Components - Product Warranty (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Product Warranty, Increase (Decrease) [Roll Forward]
Balance at the beginning of the period	$ 1,875	$ 1,088
Accruals of warranties issued	355	1,336
Settlements of warranty claims	(153)	(549)
Balance at the end of the period	$ 2,077	$ 1,875

Balance Sheet Components - Othe

Balance Sheet Components - Other Non-Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Deferred tax liabilities	$ 3,972	$ 4,171
Licensing-related cost, Noncurrent	11,463	11,506
Acquisition-related costs	1,000	2,500
Other Accrued Liabilities, Noncurrent	209	766
Total other non-current liabilities	$ 16,644	$ 18,943

Asset Acquisitions & Business_2

Asset Acquisitions & Business Combination - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Payment of acquisition-related obligations	$ 683	$ 4,323
Fair Value of Contingent Consideration
Business Acquisition [Line Items]
Payment of acquisition-related obligations		$ 4,300
Current Liabilities | Fair Value of Contingent Consideration
Business Acquisition [Line Items]
Contingent consideration for milestone payments	$ 1,300		$ 2,600

Asset Acquisitions & Business_3

Asset Acquisitions & Business Combination - Consideration Transferred (Details) - USD ($) $ in Thousands	Aug. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Change in fair value of contingent consideration		$ 0	$ 442
Payment of acquisition-related obligations		683	4,323
MVI Health Inc. [Member]
Business Acquisition [Line Items]
Payments Made Pursuant To Anti-Dilution Provision	$ 500
Cash transferred	20,000
Anti-dilution protection at Transfer Agreement date	$ 4,500
Contingent liability, non-current		1,000		$ 2,500
Contingent liability accrual, current		3,000		1,500
Asset Acquisition, Ownership Percentage	90.00%
Remaining equity interest	10.00%
MVI Health Inc. [Member]
Business Acquisition [Line Items]
Equity method ownership percentage	50.00%
Fair Value of Contingent Consideration
Business Acquisition [Line Items]
Change in fair value of contingent consideration		1,300
Payment for Contingent Consideration Liability, Operating Activities		600
Payment for Contingent Consideration Liability, Financing Activities		700
Payment of acquisition-related obligations			$ 4,300
Fair Value of Contingent Consideration | Current Liabilities
Business Acquisition [Line Items]
Fair value of contingent consideration for milestone payments		$ 1,300		$ 2,600

Intangible Assets - Intangible

Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	16 years 1 month 6 days		16 years
Finite lived intangible assets: gross carrying amount	$ 13,669		$ 13,838
Accumulated amortization	(1,713)		(1,472)
Finite lived intangible assets: net	11,956		12,366
Indefinite-lived intangible assets	14,857		14,879
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	0
Total intangible assets, gross	28,526		28,717
Total intangible assets, net	26,813		27,245
Total amortization of finite lived intangible assets	266	$ 247
Acquisition of intangible assets from a licensing agreement		$ 2,500
Licensing-related cost, Noncurrent	$ 11,463		$ 11,506
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	15 years		15 years
Finite lived intangible assets: gross carrying amount	$ 6,688		$ 6,823
Accumulated amortization	(781)		(681)
Finite lived intangible assets: net	$ 5,907		$ 6,142
Trade secrets and processes
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	20 years			20 years
Finite lived intangible assets: gross carrying amount	$ 5,256			$ 5,256
Accumulated amortization	(329)			(263)
Finite lived intangible assets: net	$ 4,927			$ 4,993
Other
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	5 years		5 years
Finite lived intangible assets: gross carrying amount	$ 1,725		$ 1,759
Accumulated amortization	(603)		(528)
Finite lived intangible assets: net	1,122		1,231
Technology Licensing Agreement
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	14,857		14,879
Loss Contingency Accrual, Period Increase (Decrease)	0
Contingent Liability Accrual	12,400		12,400
Cost of revenue
Finite-Lived Intangible Assets [Line Items]
Total amortization of finite lived intangible assets	66		31
Sales, general and administrative
Finite-Lived Intangible Assets [Line Items]
Total amortization of finite lived intangible assets	200		216
Accrued Liabilities | Technology Licensing Agreement
Finite-Lived Intangible Assets [Line Items]
Contingent liability accrual, current	900		900
Noncurrent Liabilities | Technology Licensing Agreement
Finite-Lived Intangible Assets [Line Items]
Contingent liability, non-current	$ 11,500		$ 11,500

Goodwill (Details)

Goodwill (Details)	3 Months Ended
	Mar. 31, 2019USD ($)
Goodwill [Roll Forward]
Goodwill	$ 7,813,000
Foreign currency translation	(154,000)
Goodwill	7,659,000
Impairment loss	$ 0

Leases - Schedule of Impact on

Leases - Schedule of Impact on Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets	$ 11,869	$ 11,776	$ 12,200
Total current assets	423,086	410,302	410,726
Operating lease right-of-use assets	42,376	43,277	0
Total assets	568,789	557,859	515,006
Accrued liabilities	58,032	57,754	57,886
Current operating lease liabilities	3,688	3,608	0
Total current liabilities	69,412	69,538	66,062
Deferred rent	0		7,586
Non-current operating lease liabilities	46,070	46,963	0
Total liabilities	132,126	135,444	92,591
Total liabilities and stockholders’ equity	$ 568,789	557,859	$ 515,006
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets		(424)
Total current assets		(424)
Operating lease right-of-use assets		43,277
Total assets		42,853
Accrued liabilities		(132)
Current operating lease liabilities		3,608
Total current liabilities		3,476
Deferred rent		(7,586)
Non-current operating lease liabilities		46,963
Total liabilities		42,853
Total liabilities and stockholders’ equity		$ 42,853

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Rent expense	$ 1,400
Operating lease, future minimum payments			$ 70,656
Roseville Lease
Lessee, Lease, Description [Line Items]
Operating lease term, lease not yet commenced		15 years
Operating lease, future minimum payments		$ 40,900
Minimum
Lessee, Lease, Description [Line Items]
Operating lease, renewal term		5 years
Maximum
Lessee, Lease, Description [Line Items]
Operating lease, renewal term		15 years

Leases - Summary of Lease Cost

Leases - Summary of Lease Cost (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Leases [Abstract]
Operating lease cost	$ 1,768
Variable lease cost	758
Total lease costs	$ 2,526
Weighted Average Remaining Lease Term	10 years 7 months 6 days
Weighted Average Discount Rate	6.20%

Leases - Schedule of Maturity o

Leases - Schedule of Maturity of Lease Liabilities (Details) $ in Thousands	Mar. 31, 2019USD ($)
Leases [Abstract]
Remainder of 2019	$ 5,000
2020	6,586
2021	5,887
2022	5,801
2023	5,787
2024	5,849
Thereafter	33,929
Total undiscounted lease payments	68,839
Less imputed interest	(19,081)
Present value of lease liabilities	$ 49,758

Leases - Schedule of Leases Pay

Leases - Schedule of Leases Payments Under Previous Guidance (Details) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2019	$ 6,575
2020	6,571
2021	5,809
2022	5,772
2023	5,735
Thereafter	40,194
Total future minimum lease payments	$ 70,656

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Leases [Abstract]
Operating cash flows from operating leases	$ 1,623

Commitments and Contingencies -

Commitments and Contingencies - Royalty Obligations (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Other Commitments [Line Items]
Finite lived intangible assets: gross carrying amount	$ 13,669,000		$ 13,838,000
Cost of revenue
Other Commitments [Line Items]
Royalty expense	1,100,000	$ 700,000
Royalty Agreement, March 2005
Other Commitments [Line Items]
Minimum annual royalty payments	$ 100,000		$ 100,000
Term of agreement	15 years
Royalty Agreement, April 2012
Other Commitments [Line Items]
Term of agreement	15 years
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%
Trade secrets and processes
Other Commitments [Line Items]
Finite lived intangible assets: gross carrying amount	$ 5,256,000			$ 5,256,000

Stockholder's Equity - Common S

Stockholder's Equity - Common Stock (Details)	3 Months Ended
	Mar. 31, 2018shares
Restricted Stock Units (RSUs)
Subsidiary, Sale of Stock [Line Items]
Granted (in shares)	53,256

Stockholder's Equity - Stock Op

Stockholder's Equity - Stock Option Activity (Details)	3 Months Ended
	Mar. 31, 2019$ / sharesshares
Number of Shares
Beginning balance (in shares) | shares	1,688,881
Options exercised (in shares) | shares	(89,451)
Options cancelled (in shares) | shares	(3,175)
Ending balance (in shares) | shares	1,596,255
Weighted-Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 18.91
Options exercised (in dollars per share) | $ / shares	11.97
Options cancelled (in dollars per share) | $ / shares	21.94
Ending balance (in dollars per share) | $ / shares	$ 19.29

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, 2019$ / sharesshares
Number of Shares
Unvested beginning balance (in shares)	451,463
Granted (in shares)	63,113
Vested (in shares)	(51,147)
Canceled/Forfeited (in shares)	(1,350)
Unvested and expected to vest ending balance (in shares)	462,079
Weighted -Average Grant Date Fair Value
Unvested beginning balance (in dollars per share) | $ / shares	$ 57.29
Granted (in dollars per share) | $ / shares	146.80
Vested (in dollars per share) | $ / shares	60.82
Canceled/Forfeited (in dollars per share) | $ / shares	92.69
Unvested and expected to vest ending balance (in dollars per share) | $ / shares	$ 69.02
Restricted stock and RSUs expected to vest (shares)	449,313

Stockholder's Equity - Stock-ba

Stockholder's Equity - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 5,095	$ 4,154
Unrecognized compensation cost related to unvested share-based compensation arrangements	$ 25,800
Unrecognized compensation cost, expected recognition period	2 years 6 months
Share-based compensation expense, capitalized in inventory	$ 500		$ 400
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	291	219
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	524	368
Sales, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 4,280	$ 3,567

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 422,240
Amounts reclassified from accumulated other comprehensive income to earnings:
Total other comprehensive (loss) income, net of tax	(636)	$ 1,068
Ending balance	436,732
Marketable Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(500)	(235)
Other comprehensive (loss) income before reclassifications:
Other comprehensive income before reclassifications	462	(386)
Income tax effect — (expense) benefit	0	68
Net of tax	462	(318)
Amounts reclassified from accumulated other comprehensive income to earnings:
Realized gains — marketable investments	0	0
Income tax effect — expenses	0	0
Net of tax	0	0
Total other comprehensive (loss) income, net of tax	462	(318)
Ending balance	(38)	(553)
Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(1,442)	1,804
Other comprehensive (loss) income before reclassifications:
Other comprehensive income before reclassifications	(1,098)	1,608
Income tax effect — (expense) benefit	0	(222)
Net of tax	(1,098)	1,386
Amounts reclassified from accumulated other comprehensive income to earnings:
Realized gains — marketable investments	0	0
Income tax effect — expenses	0	0
Net of tax	0	0
Total other comprehensive (loss) income, net of tax	(1,098)	1,386
Ending balance	(2,540)	3,190
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(1,942)	1,569
Other comprehensive (loss) income before reclassifications:
Income tax effect — (expense) benefit	0	(154)
Net of tax	(636)	1,068
Amounts reclassified from accumulated other comprehensive income to earnings:
Realized gains — marketable investments	0	0
Income tax effect — expenses	0	0
Net of tax	0	0
Total other comprehensive (loss) income, net of tax	(636)	1,068
Ending balance	$ (2,578)	$ 2,637

Income Taxes Income Taxes (Deta

Income Taxes Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Tax Contingency [Line Items]
Provision for (benefit from) income taxes	$ 1,455	$ (1,938)
Effective tax rate	12.20%	(43.00%)

Net Income per Share - Basic an

Net Income per Share - Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net income attributable to Penumbra, Inc.	$ 10,698	$ 5,491
Denominator:
Weighted average shares used to compute net (loss) income per share attributable to common stockholders — Basic (in shares)	34,507,279	33,846,142
Potential dilutive shares (in shares)	1,705,885	2,070,909
Weighted average shares used to compute net income attributable to common stockholders —Diluted (in shares)	36,213,164	35,917,051
Net (loss) income per share attributable to common stockholders — Basic (in dollars per share)	$ 0.31	$ 0.16
Net (loss) income per share attributable to common stockholders — Diluted (in dollars per share)	$ 0.30	$ 0.15

Net Income per Share - Antidilu

Net Income per Share - Antidilutive Securities (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from the computation of earnings per share (in shares)	57,200	23,900

Revenues - Disaggregation of R

Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 128,439	$ 102,701
Revenues	128,439	102,701
United States
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	82,511	65,801
Japan
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	9,522	10,682
Other International
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	36,406	26,218
Neuro
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	81,471	71,433
Vascular
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 46,968	$ 31,268

Uncategorized Items - pen-20190

Label	Element	Value
Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 464,000
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 464,000