Nevro (NVRO) 10-Q 4 May 22 2022 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2022	Apr. 27, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Trading Symbol	NVRO
Entity Registrant Name	Nevro Corp.
Entity Central Index Key	0001444380
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Small Business	false
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		35,260,684
Entity File Number	001-36715
Entity Tax Identification Number	56-2568057
Entity Address, Address Line One	1800 Bridge Parkway
Entity Address, City or Town	Redwood City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94065
City Area Code	650
Local Phone Number	251-0005
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Security Exchange Name	NYSE
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock, $0.001 par value per share

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets
Cash and cash equivalents	$ 49,471	$ 34,710
Short-term investments	274,171	327,317
Accounts receivable, net of allowance for doubtful accounts of $1,237 and $1,385 at March 31, 2022 and December 31, 2021, respectively	63,054	70,475
Inventories	90,588	93,517
Prepaid expenses and other current assets	13,095	5,185
Total current assets	490,379	531,204
Property and equipment, net	20,837	20,664
Operating lease assets	16,569	17,577
Other assets	4,488	4,493
Restricted cash	606	606
Total assets	532,879	574,544
Current liabilities
Accounts payable	27,135	31,999
Accrued liabilities	38,326	45,517
Other current liabilities	4,863	4,687
Total current liabilities	70,324	82,203
Long-term debt	185,953	151,310
Long-term operating lease liabilities	14,185	15,402
Other long-term liabilities	22,031	22,013
Total liabilities	292,493	270,928
Commitments and contingencies (Note 6)
Stockholders’ equity
Preferred stock, $0.001 par value, 10,000,000 shares authorized at March 31, 2022 and December 31, 2021; zero shares issued and outstanding at March 31, 2022 and December 31, 2021
Common stock, $0.001 par value, 290,000,000 shares authorized at March 31, 2022 and December 31, 2021; 35,876,367 and 35,709,570 shares issued at March 31, 2022 and December 31, 2021, respectively; 35,193,451 and 35,026,654 shares outstanding at March 31, 2022 and December 31, 2021, respectively	35	35
Additional paid-in capital	886,451	928,138
Accumulated other comprehensive income (loss)	(1,577)	(364)
Accumulated deficit	(644,523)	(624,193)
Total stockholders’ equity	240,386	303,616
Total liabilities and stockholders’ equity	$ 532,879	$ 574,544

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Statement Of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 1,237	$ 1,385
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	290,000,000	290,000,000
Common stock, shares issued	35,876,367	35,709,570
Common stock, shares outstanding	35,193,451	35,026,654

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Statement [Abstract]
Revenue	$ 87,842	$ 88,610
Cost of revenue	28,750	26,316
Gross profit	59,092	62,294
Operating expenses
Research and development	12,536	11,534
Sales, general and administrative	79,325	73,272
Total operating expenses	91,861	84,806
Loss from operations	(32,769)	(22,512)
Interest income	143	297
Interest expense	(1,603)	(6,547)
Other income (expense), net	85	(457)
Loss before income taxes	(34,144)	(29,219)
Provision for income taxes	181	342
Net loss	(34,325)	(29,561)
Other comprehensive loss:
Changes in foreign currency translation adjustment	(192)	(312)
Changes in unrealized gains on short-term investments, net	(1,021)	(147)
Net change in other comprehensive loss	(1,213)	(459)
Comprehensive loss	$ (35,538)	$ (30,020)
Net loss per share, basic and diluted	$ (0.98)	$ (0.85)
Weighted average number of common shares used to compute basic and diluted net loss per share	35,073,862	34,633,749

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (unaudited) - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member]Cumulative Effect, Period of Adoption, Adjustment [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member]Cumulative Effect, Period of Adoption, Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balances at Dec. 31, 2020	$ 388,460		$ 35	$ 880,660		$ (492,833)		$ 598
Beginning balances, shares at Dec. 31, 2020			34,583,064
Exercise of common stock options	1,331			1,331
Exercise of common stock options, shares			28,152
Issuance of common stock upon release of restricted stock units			99,389
Shares withheld for tax obligations	(2,801)			(2,801)
Shares withheld for tax obligations, shares			(17,886)
Stock based compensation	9,235			9,235
Net loss	(29,561)					(29,561)
Change in other comprehensive loss	(459)							(459)
Ending balances at Mar. 31, 2021	366,205		$ 35	888,425		(522,394)		139
Ending balances, shares at Mar. 31, 2021			34,692,719
Beginning balances at Dec. 31, 2021	303,616	$ (34,345)	$ 35	928,138	$ (48,340)	(624,193)	$ 13,995	(364)
Beginning balances, shares at Dec. 31, 2021			35,026,654
Accounting Standards Update [Extensible Enumeration]		ASU 2020-06 [Member]			ASU 2020-06 [Member]		ASU 2020-06 [Member]
Exercise of common stock options	545			545
Exercise of common stock options, shares			10,642
Issuance of common stock upon release of restricted stock units			263,412
Shares withheld for tax obligations	(7,298)			(7,298)
Shares withheld for tax obligations, shares			(107,257)
Stock based compensation	13,406			13,406
Net loss	(34,325)					(34,325)
Change in other comprehensive loss	(1,213)							(1,213)
Ending balances at Mar. 31, 2022	$ 240,386		$ 35	$ 886,451		$ (644,523)		$ (1,577)
Ending balances, shares at Mar. 31, 2022			35,193,451

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities
Net loss	$ (34,325)	$ (29,561)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	1,495	1,101
Amortization of operating lease assets	1,008	886
Stock-based compensation expense	13,408	9,237
Amortization of premium (accretion of discount) on short-term investments	449	435
Provision for doubtful accounts	(50)	(831)
Write-down of inventory	1,086	1,545
Amortization of debt discount and issuance costs	298	4,487
Unrealized (gains) losses on foreign currency transactions	252	1,330
Changes in operating assets and liabilities
Accounts receivable	7,015	12,141
Inventories	1,919	(5,639)
Prepaid expenses and other current assets	(7,915)	(6,153)
Other assets	3	253
Accounts payable	(5,190)	5,871
Accrued liabilities	(6,673)	(1,011)
Other long-term liabilities	(1,198)	(962)
Net cash used in operating activities	(28,418)	(6,871)
Cash flows from investing activities
Purchases of short-term investments	(40,226)	(147,658)
Proceeds from maturity of short-term investments	91,900	200,555
Purchases of property and equipment	(1,607)	(2,555)
Net cash provided by (used in) investing activities	50,067	50,342
Cash flows from financing activities
Minimum tax withholding paid on behalf of employees for net share settlement	(7,298)	(2,801)
Proceeds from issuance of common stock to employees	545	1,331
Net cash provided by financing activities	(6,753)	(1,470)
Effect of exchange rate changes on cash and cash equivalents	(135)	(61)
Net increase (decrease) in cash, cash equivalents and restricted cash	14,761	41,940
Cash, cash equivalents and restricted cash
Cash, cash equivalents and restricted cash at beginning of period	35,316	45,203
Cash, cash equivalents and restricted cash at end of period	50,077	87,143
Significant non-cash transactions
Purchases of property and equipment in accounts payable	$ 585	$ 1,170

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies Basis of Presentation The accompanying interim condensed consolidated financial statements as of March 31, 2022 and for the three months ended March 31, 2022 and 2021, and the related interim information contained within the notes to the financial statements, are unaudited. The unaudited interim condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (U.S. GAAP) for interim financial information and on the same basis as the audited financial statements included on the Company’s Annual Report on Form 10-K (Annual Report) filed with the Securities and Exchange Commission (SEC) on February 23, 2022. The condensed consolidated financial statements are prepared in U.S. dollars and include the Company’s accounts and those of its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated. In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements contain all adjustments (consisting of normal recurring adjustments) necessary to state fairly the Company’s financial position as of March 31, 2022, and the results of its operations and cash flows for the three months ended March 31, 2022 and 2021. All such adjustments are of a normal and recurring nature. The interim financial data as of March 31, 2022 is not necessarily indicative of the results to be expected for the year ending December 31, 2022, or for any future period. The consolidated balance sheet as of December 31, 2021 was derived from the audited financials as of that date. The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2021 included in the Annual Report. Use of Estimates The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Estimates are based on historical experience, where applicable, and other assumptions believed to be reasonable by the management. Actual results may differ from those estimates under different assumptions or conditions. The COVID-19 pandemic h as negatively impacted, and may continue to negatively impact the Company’s operations and revenues and overall financial condition Foreign Currency Translation Unrealized foreign exchange gains and losses from the remeasurement of assets and liabilities denominated in currencies other than the functional currency of the reporting entity are recorded in other income (expense), net. Additionally, realized gains and losses resulting from transactions denominated in currencies other than the local currency are recorded in other income (expense), net in the condensed consolidated statements of operations and comprehensive loss. The Company recorded net unrealized and net realized foreign currency transaction gains (losses) during the periods presented as follows (in thousands): Three Months Ended March 31, 2022 2021 Net unrealized foreign currency gain (loss) $ 166 $ (1,452 ) Net realized foreign currency gain (loss) (75 ) 1,002 Recent Accounting Pronouncements Accounting Pronouncements Recently Adopted In August 2020, the FASB issued ASU No. 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (Subtopic 815-40) conversion features as a component of equity. Instead, entities will account for the convertible debt as a single unit of account, unless the conversion feature requires bifurcation and recognition as derivatives. Additionally, the guidance requires entities to use the if-converted method for all convertible instruments in the diluted earnings per share calculation and include the effect of potential share settlement for instruments that may be settled in cash or shares. The Company adopted ASU 2020-06 on January 1, 2022 using the modified retrospective method as of January 1, 2022. The adoption of ASU 2020-06 resulted in an increase of $ 34.3 million to reflect the full principal amount of the 2025 Notes, net of debt issuance costs, a reduction of $ 48.3 million to additional paid-in capital to remove the equity component separately recorded for the conversion features and the debt issuance costs allocated to the conversion feature and a cumulative-effect adjustment of $ 14.0 million reducing the beginning balance of accumulated deficit as of January 1, 2022. Upon the adoption of ASU 2020-06, interest expense is reduced as the Company no longer recognizes any amortization of debt discounts as interest expense, due to the removal of the unamortized debt discounts. In addition, the use of the if-converted method for the 2025 Notes in calculating diluted net income (loss) per share calculation under ASU 2020-06 had no impact to the number of potentially dilutive shares in each of the periods presented. The cumulative effect of the changes made to the consolidated balance sheet as of January 1, 2022 for the adoption of ASU 2020-06 were as follows (in thousands): Balance at Adjustments Due Balance at December 31, 2021 to ASU 2020-06 January 1, 2022 Long term debt $ 151,310 $ 34,345 $ 185,655 Additional paid-in capital $ 928,138 $ (48,340 ) $ 879,798 Accumulated deficit $ (624,193 ) $ 13,995 $ (610,198 ) Significant Accounting Policies With the exception of the policies and accounting pronouncements above, there have been no other material changes to the Company’s significant accounting policies from its Annual Report on Form 10-K for the fiscal year ended December 31, 2021.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2022
Revenue From Contract With Customer [Abstract]
Revenue	2. Revenue The following table presents revenue by geography, based on the billing address of the customer (in thousands): Three Months Ended March 31, 2022 2021 United States $ 73,214 $ 74,737 International 14,628 13,873 Total revenue $ 87,842 $ 88,610 The United States is the only country that accounts for 10% or more of the revenue during the periods presented: Three Months Ended March 31, 2022 2021 United States 83 % 84 % There were no customers that accounted for 10% or more of the Company’s revenue for each of the three months ended March 31, 2022 and 2021. Additionally, there were no customers that accounted for 10% or more of the Company’s accounts receivable balance as of March 31, 2022 and December 31, 2021. For each of the three months ended March 31, 2022 and 2021, the Company recognized a recovery of bad debt expenses of $0.1 million, respectively In July 2021, the Company received FDA approval of its proprietary 10 kHz Therapy for the management of chronic intractable pain of the lower limbs, including unilateral or bilateral pain, associated with painful diabetic neuropathy (PDN). For the three months ended March 31, 2022, PDN represented 7% of worldwide permanent implant procedures, which resulted in approximately $6.0 million in revenue. The Company classifies PDN revenue by using estimates and assumptions based on historical experiences and knowledge of current conditions, given available information.

Lease Accounting

Lease Accounting	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Lease Accounting	3. Lease Accounting The Company has operating leases for office space, a manufacturing facility, warehouse, research and development facilities and equipment. Leases with terms of 12 months or less are not recorded on the balance sheet, as the related lease expenses are recognized on a straight-line basis over the lease term. The Company accounts for lease components (such as fixed payments) separately from non-lease components (such as common area expenses). The weighted average lease terms and discounts rates are as follows: March 31, 2022 December 31, 2021 Operating Lease Term and Discount Rate Weighted-average remaining lease term 3.98 years 4.20 years Weighted-average discount rate 7.0% 7.0% As of March 31, 2022, t he maturity of lease liabilities are as follows (in thousands): Operating Leases 2022, remaining months $ 4,345 2023 6,019 2024 6,201 2025 2,849 2026 405 Thereafter 1,978 Total lease payments 21,797 Less: Interest (2,848 ) Present value of lease liabilities $ 18,949 Supplemental lease cost information are as follows (in thousands): Three Months Ended March 31, 2022 2021 Operating lease cost $ 1,342 $ 1,234 Supplemental balance sheet information are as follows (in thousands): March 31, 2022 December 31, 2021 Operating Leases: Operating lease assets $ 16,569 $ 17,577 Other current liabilities $ 4,764 $ 4,588 Long term operating lease liabilities 14,185 15,402 Total operating lease liabilities $ 18,949 $ 19,990 Supplemental cash flow information are as follows (in thousands): Three Months Ended March 31, 2022 2021 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flow from operating leases $ 1,375 $ 1,248 See Note 6 for further details of the Company’s lease commitments.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements Cash Equivalents and Short-Term Investments The Company’s cash equivalents are comprised of investments in money market funds that are classified as Level 1 of the fair value hierarchy. The Company’s money market funds are classified within Level 1 of the fair value hierarchy and are valued based on quoted prices in active markets for identical securities. The Company’s short-term investments are comprised of agency bonds, commercial paper, corporate notes and treasury bonds. All short-term investments have been classified within Level 1 or Level 2 of the fair value hierarchy because of the sufficient observable inputs for revaluation. The Company’s Level 2 investments are valued using third-party pricing sources. The pricing services utilize industry-standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar investments, issuer credit spreads, benchmark investments, prepayment/default projections based on historical data and other observable inputs. The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): Balance as of March 31, 2022 Level 1 Level 2 Level 3 Total Assets: Money market funds (i) $ 28,796 $ — $ — $ 28,796 Agency bonds (ii) — 32,514 — 32,514 Corporate notes (ii) — 20,196 — 20,196 Treasury bonds (ii) 221,461 — — 221,461 Total assets $ 250,257 $ 52,710 $ — $ 302,967 Balance as of December 31, 2021 Level 1 Level 2 Level 3 Total Assets: Money market funds (i) $ 9,562 $ — $ — $ 9,562 Agency bonds (ii) — 42,538 — 42,538 Commercial paper (ii) — 61,884 — 61,884 Corporate notes (iii) — 30,351 — 30,351 Treasury bonds (ii) 197,552 — — 197,552 Total assets $ 207,114 $ 134,773 $ — $ 341,887 (i) Included in cash and cash equivalents on the condensed consolidated balance sheets. (ii) Included in short-term investments on the condensed consolidated balance sheets. (i i i ) Included in cash and cash equivalents or short-term investments on the condensed consolidated balance sheets. Convertible Senior Notes As of March 31, 2022 and December 31, 2021, the fair value of the 2.75% convertible senior notes due 2025 was $204.0 million and $212.0 million, respectively. The fair value was determined on the basis of market prices observable for similar instruments and is considered Level 2 in the fair value hierarchy (See Note 7).

Balance Sheet Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2022
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Components	5. Balance Sheet Components Cash and Cash Equivalents The Company considers all highly-liquid investments purchased with an original maturity of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents include money market funds in the amount of $28.8 million and $9.6 million as of March 31, 2022 and December 31, 2021, respectively. At March 31, 2022 and December 31, 2021, the Company’s cash equivalents were held at institutions in the United States and include deposits in a money market fund which was unrestricted as to withdrawal or use. The Company also held cash in foreign banks of approximately $13.2 million at March 31, 2022 and $8.6 million at December 31, 2021 that was not insured. The Company has not experienced any losses on its deposits of cash and cash equivalents. Investments The fair value of the Company’s cash equivalents and short-term investments approximates their respective carrying amounts due to their short-term maturity. The following is a summary of the gross unrealized gains and unrealized losses on the Company’s investment securities, excluding investments in money market funds (in thousands): March 31, 2022 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value Investment Securities Agency bonds $ 32,520 $ — $ (6 ) $ 32,514 Corporate notes 20,218 — (22 ) 20,196 Treasury bonds 222,820 — (1,359 ) 221,461 Total securities $ 275,558 $ — $ (1,387 ) $ 274,171 December 31, 2021 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value Investment Securities Agency bonds $ 42,546 $ — $ (8 ) $ 42,538 Commercial paper 61,886 2 (4 ) 61,884 Corporate notes 30,371 — (20 ) 30,351 Treasury bonds 197,889 2 (339 ) 197,552 Total securities $ 332,692 $ 4 $ (371 ) $ 332,325 Realized gains or losses and other-than-temporary impairments, if any, on available-for-sale securities are reported in other income (expense), net as incurred. The cost of securities sold is determined based on the specific identification method. The amount of realized gains and realized losses on investments recorded for the periods presented has not been material. The contractual maturities of the Company’s investment securities as of March 31, 2022 were as follows (in thousands): Amortized Cost Fair Value Amounts maturing within one year $ 253,942 $ 252,830 Amounts maturing after one year through five years 21,616 21,341 Total investment securities $ 275,558 $ 274,171 Inventories (in thousands) March 31, December 31, 2022 2021 Raw materials $ 42,079 $ 50,160 Finished goods 48,509 43,357 Total inventories $ 90,588 $ 93,517 Inventories are stated at the lower of cost or net realizable value. Cost is determined using the standard cost method which approximates the first-in, first-out basis. Net realizable value is determined as the prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The Company regularly reviews inventory quantities compared to forecasted sales to record a provision for excess and obsolete inventory when appropriate. Inventory write-downs are recorded for excess and obsolete inventory. The Company estimates forecasted sales by considering product acceptance in the marketplace, customer demand, historical sales, product obsolescence and technological innovations. The Company’s policy is to write down inventory that has become obsolete, inventory that has a cost basis in excess of its expected lower of cost or net realizable value, and inventory in excess of expected requirements. The estimate of excess quantities is judgmental and primarily dependent on the Company’s estimates of future demand for a particular product. If the estimate of future demand is inaccurate based on actual sales, the Company may increase the write-down for excess inventory for that component and record a charge to inventory impairment in the accompanying consolidated statements of operations and comprehensive loss. The Company periodically evaluates the carrying value of inventory on hand for potential excess amount over demand using the same lower of cost or net realizable value approach as that has been used to value the inventory. The Company also periodically evaluates inventory quantities in consideration of actual loss experience. As a result of these evaluations, the Company recognized total write-downs of $1.1 million and $1.5 million for the three months ended March 31, 2022 and 2021, respectively. T Property and Equipment, Net (in thousands) March 31, December 31, 2022 2021 Laboratory equipment $ 10,368 $ 8,722 Computer equipment and software 16,993 16,349 Furniture and fixtures 4,302 4,215 Leasehold improvements 10,562 10,316 Construction in process 2,762 3,717 Total 44,987 43,319 Less: Accumulated depreciation and amortization (24,150 ) (22,655 ) Property and equipment, net $ 20,837 $ 20,664 The Company recognized depreciation and amortization expense on property and equipment as follows (in thousands): Three Months Ended March 31, 2022 2021 Depreciation and amortization expense $ 1,495 $ 1,101 Accrued Liabilities (in thousands) March 31, December 31, 2022 2021 Accrued payroll and related expenses $ 26,459 $ 30,957 Accrued professional fees 2,785 6,547 Accrued taxes 1,819 1,074 Accrued clinical and research expenses 241 305 Accrued interest 2,609 1,305 Accrued warranty 452 664 Accrued other 3,961 4,665 Total accrued liabilities $ 38,326 $ 45,517

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2022
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Operating Leases In March 2015, the Company entered into a lease agreement for approximately 50,000 square feet of office space located in Redwood City, California for a period beginning on June 30, 2015 and ending in May 2022, with initial annual payments of approximately $2.0 million, increasing to $2.4 million annually during the final year of the lease term . In December 2016, the Company entered into a first amendment to the lease for an additional approximately 50,000 square feet of office space adjacent to the premises under the original lease (the Expansion Premises), with initial annual payments of $1.2 million, increasing to $2.9 million in the final year of the amended lease term. The lease for the Expansion Premises commenced on June 1, 2018 The Company entered into a separate non-cancellable facility lease for warehouse space beginning on March 1, 2017 through February 28, 2022, under which it is obligated to pay approximately $0.4 million in lease payments over the term of the lease. In October 2021, the Company entered into a first amendment of the warehouse lease, which extends the lease term to terminate on May 31, 2025 and under which the Company is obligated to pay approximately $ 0.4 million over the term of the extension period. In August 2020, the Company entered into a lease for approximately 35,411 square feet of space for a manufacturing facility in Costa Rica to begin in April 2021 June 2031 See Note 3 for further discussion on Lease Accounting. Warranty Obligations The Company provides a limited one- to five-year warranty and warrants that its products will operate substantially in conformity with product specifications. The Company records an estimate for the provision for warranty claims in cost of revenue when the related revenues are recognized. This estimate is based on historical and anticipated rates of warranty claims, the cost per claim and the number of units sold. The Company regularly assesses the adequacy of its recorded warranty obligations and adjusts the amounts as necessary. Activities related to warranty obligations were as follows (in thousands): Three Months Ended March 31, 2022 2021 Beginning balance $ 664 $ 699 Provision for warranty 715 695 Utilization (927 ) (543 ) Ending balance $ 452 $ 851 Contingencies From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of business activities related to, for example, employment matters and patent issues. 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. When determining the estimated loss or range of loss, significant judgement is required. The Company accrued a loss contingency of $20.0 million at September 30, 2021 related to the Delaware I Legal Matters Indemnification The Company enters into standard indemnification arrangements in the ordinary course of business. Pursuant to these arrangements, the Company indemnifies, holds harmless and agrees to reimburse the indemnified parties for losses suffered or incurred by the indemnified party, 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 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 maximum potential amount of future payments the Company could be required to make under these indemnification agreements is unlimited; however, the Company has director and officer insurance coverage that reduces the Company’s exposure and enables the Company to recover a portion of any future amounts paid. The Company believes the estimated fair value of these indemnification agreements in excess of applicable insurance coverage is minimal. Legal Matters Boston Scientific Litigations California Litigation Related to High Frequency On November 28, 2016, the Company filed a lawsuit for patent infringement against Boston Scientific Corporation and Boston Scientific Neuromodulation Corporation (collectively, Boston Scientific). The lawsuit, filed in the U.S. District Court for the Northern District of California (the California Court), asserted that Boston Scientific was infringing, or would soon begin infringing, seven of the Company’s patents covering inventions relating to the Senza system and 10 kHz Therapy. Shortly after the Company filed this lawsuit in 2016, Boston Scientific cancelled its original launch plan and modified its SCS system to avoid infringing the asserted patents. On July 24, 2018, the California Court issued an order on claim construction and summary judgment. In the order, the California Court ruled that the Company’s asserted method claims were patent eligible and not invalid as indefinite. Collectively, the asserted method claims cover methods for delivering SCS therapy at frequencies between 1.5 kHz and 100 kHz. The California Court, however, found that Boston Scientific was not currently infringing the six upheld method claims because Boston Scientific cancelled its original launch plans and ultimately never practiced the asserted method claims in the United States. Specifically, the California Court found that Boston Scientific's sale of the Spectra WaveWriter systems for commercial use in the United States did not infringe the upheld method claims because Boston Scientific modified the Spectra WaveWriter systems to prevent them from being programmed to generate signals above 1.2 kHz. The California Court also found that the Company’s asserted system claims were invalid as indefinite. As discussed below, the California Court’s finding of invalidity was overturned by the U.S. Court of Appeals for the Federal Circuit (the Federal Circuit). On July 31, 2018, the parties entered into an agreement to dismiss the Company’s declaratory judgment claims, without prejudice, so that the Company and Boston Scientific could each appeal portions of the California Court’s July 24th ruling to the Federal Circuit. On April 9, 2020, the Federal Circuit returned its ruling, which vacated and remanded the California Court’s judgment of invalidity. As a result of the Federal Circuit’s ruling, the system claims invalidated by the California Court were reinstated, and thus all of the Company’s asserted claims remain valid and enforceable. On December 14, 2020, the parties agreed to the final dismissal of all remaining claims before the California Court based on Boston Scientific’s assertion to the court that it did not have any current plans to commercially launch a high frequency SCS system in the United States. The California Court entered the agreed upon dismissal on December 16, 2020. Delaware Litigations Unrelated to High Frequency On December 9, 2016, Boston Scientific filed a patent infringement lawsuit alleging the Company’s manufacture, use and sale of the Senza system infringes ten of Boston Scientific’s patents covering spinal cord stimulation technology related to stimulation leads, rechargeable batteries and telemetry (the Delaware I litigation). On April 27, 2018, Boston Scientific filed a second lawsuit alleging patent infringement of In relation to the Delaware I litigation, the Company filed petitions for inter partes inter partes inter partes Through various orders from the court, portions of Boston Scientific’s Delaware I case were dismissed, and portions of Boston Scientific’s Delaware II case have been stayed for future litigation. The stay of the Delaware II litigation was lifted on April 2022, and the case is expected to proceed to a trial in 2023. In relation to the Delaware I case, of the ten patents originally asserted on December 9, 2016, Boston Scientific proceeded to trial with four patents directed to SCS leads and lead manufacturing techniques. On November 1, 2021, a Delaware jury found that the Company infringed Boston Scientific’s patents U.S. 7,891,085 (“the ‘085 patent”) and U.S. 8,019,439, and that the Company did not infringe Boston Scientific’s patents U.S. 8,646,172 and U.S. 8,650,747. With regard to the ‘085 patent, the jury found that the infringement was willful, though the infringement of the ‘085 patent was only directed to a limited number of SCS leads that the Company sold internationally between 2012 and 2014. Boston Scientific does not assert that the Company continues to infringe the ‘085 patent. The Delaware jury awarded Boston Scientific $20.0 million. The Company disagrees with this decision and plans to appeal, which could take approximately 18-24 months to resolve. The jury award will not be paid until after the conclusion of the appeal process. In relation to the Delaware II litigation, the Company also filed counterclaims against Boston Scientific, alleging patent infringement of five Nevro patents. In March 2021, on the basis of Boston Scientific’s petition, the PTAB initiated inter partes inter partes PTAB invalidated all of the challenged claims of Nevro’s U.S. Patent No. 9,002,460. The Company expects litigation to proceed for the remaining three counterclaim patents, and for a trial to be held for the three counterclaim patents in 2023. On February 23, 2021, the Company filed a patent infringement lawsuit against Boston Scientific alleging that its January 2021 launch of the WaveWriter Alpha™ SCS System infringes five of the Company’s patents covering spinal cord stimulation technology related to delivering paresthesia-free therapy at frequencies below 1,200 Hz. The lawsuit, filed in the U.S. District Court for the District of Delaware (the Delaware III litigation), seeks unspecified damages and attorney’s fees, as well as preliminary and/or permanent injunctive relief against further infringement. The Company expects that a trial for the Delaware III litigation will be held in October 2023. With regard to the Delaware III litigation, Boston Scientific filed inter partes inter partes As of March 31, 2022, the Company recorded a liability of $20.0 Delaware I case Stimwave Litigation On February 14, 2019, the Company filed a lawsuit for patent infringement against Stimwave Technologies, Inc. (Stimwave) in the Delaware Court asserting that Stimwave was infringing the Company’s patents covering inventions related to its 10 kHz Therapy and the Senza system, as well as a claim for false advertising under the Lanham Action Section 43(a), 15 U.S.C. § 1125(a). In relation to this lawsuit, on July 24, 2019, the Delaware Court granted the Company’s motion for preliminary injunction, and issued an order barring Stimwave, and all affiliated persons and entities, from infringing patent claims covering frequencies between 3 kHz and 10 kHz. On February 27, 2020, the Company and Stimwave entered into a Settlement Agreement, in which Stimwave agreed to cease commercialization of all high frequency spinal cord stimulation systems worldwide. Stimwave also agreed to entry of a permanent injunction in the Delaware Court, under which Stimwave’s products will not deliver spinal cord stimulation therapy that includes pulse frequencies between 1,500 Hz and 100,000 Hz. The permanent injunction was filed with the Delaware Court and entered on March 2, 2020. After the Delaware Court entered the permanent injunction, the case (including Stimwave’s appeal of the preliminary injunction order) were dismissed. As part of the permanent injunction filing, Stimwave acknowledged the validity of the patents Nevro asserted in the litigation. Per the Company’s request, the permanent injunction order does not enjoin Stimwave from providing follow-up care and programming for any patients who were already programmed with high frequency therapy in the United States prior to March 6, 2020, and in the rest of the world prior to April 30, 2020. Nalu Litigation On February 28, 2020, the Company filed a lawsuit in the Delaware Court for patent infringement against Nalu Medical, Inc. (Nalu) asserting that Nalu is infringing the Company’s patents covering inventions related to its 10 kHz Therapy and the Senza system. The Company is and may from time to time continue to be involved in various legal proceedings to defend its intellectual property, including several pending European patent oppositions at the European Patent Office (EPO) initiated by the Company’s competitors Medtronic and Boston Scientific, an entitlement action filed by Boston Scientific in Germany, and an invalidity proceeding in China. In addition, the Company is and may from time to time also be involved in various legal proceedings of a character normally incident to the ordinary course of business, such as employment matters, product liability matters, and professional liability matters, which the Company does not deem to be material to its business and condensed consolidated financial statements at this stage.

Debt

Debt	3 Months Ended
	Mar. 31, 2022
Debt Disclosure [Abstract]
Debt	7. Debt 2021 Notes and Convertible Note Hedge and Warrant Transactions On June 1, 2021, the 2021 Notes matured and the Company settled the 2021 Notes. The Company paid $172.5 million to settle the outstanding principal and issued 682,912 shares of common stock to holders who elected to convert the 2021 Notes. In addition, the Company exercised its option under the bond hedge and received 682,916 shares of common stock from the bank counterparties. On the balance sheet, these shares are shown as issued but not outstanding. As of March 31, 2022, the 2021 Notes were no longer outstanding. 2025 Notes and Convertible Note Hedge and Warrant Transactions In April 2020, the Company issued $ 165.0 million aggregate principal amount of 2.75 % convertible senior notes due 2025 in a registered underwritten public offering and an additional $ 24.8 million aggregate principal amount of such notes pursuant to underwriters’ exercise in full of their option to purchase additional 2025 Notes. The interest rates are fixed at 2.75% per annum and are payable semi-annually in arrears on April 1 and October 1 of each year, commencing on October 1, 2020 . The total net proceeds from the debt offering, after deducting initial purchase discounts and debt issuance costs, were approximately $ 183.6 million. Each $1,000 principal amount of the 2025 Notes will initially be convertible into 9.5238 shares of the Company’s common stock, which is equivalent to an initial conversion price of approximately $105.00 per share, subject to adjustment upon the occurrence of specified events. The 2025 Notes will be convertible at the option of the holders at any time prior to the close of business on the business day immediately preceding October 1, 2024, only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on June 30, 2020 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (2) during the five business day period after any ten consecutive trading day period (the measurement period) in which the trading price (as defined in the indenture to the 2025 Notes) per $1,000 principal amount of notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; or (3) upon the occurrence of specified corporate events. On or after October 1, 2024 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their 2025 Notes at any time, regardless of the foregoing circumstances. Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of the Company’s common stock or a combination of cash and shares of the Company’s common stock, at the Company’s election. If the Company undergoes a fundamental change prior to the maturity date, holders of the notes may require the Company to repurchase for cash all or any portion of their notes at a repurchase price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date. In addition, if specific corporate events occur prior to the applicable maturity date, the Company will increase the conversion rate for a holder who elects to convert their notes in connection with such a corporate event in certain circumstances. During the three months ended March 31, 2022, the conditions allowing holders of the 2025 Notes to convert have not been met. Therefore, the 2025 Notes are not convertible during the three months ended June 30, 2022. As of March 31, 2022, the if-converted value of the 2025 Notes did not exceeded the principal value of those notes. In connection with the offering of the 2025 Notes, the Company entered into convertible note hedge transactions with certain bank counterparties in which the Company has the option to purchase initially (subject to adjustment for certain specified events) a total of approximately 1.8 million shares of the Company’s common stock at a price of approximately $105.00 per share. The total cost of the convertible note hedge transactions was $52.4 million. In addition, the Company sold warrants to certain bank counterparties whereby the holders of the warrants have the option to purchase initially (subject to adjustment for certain specified events) a total of approximately 1.8 million shares of the Company’s common stock at a price of $147.00 per share. The Company received $34.9 million in cash proceeds from the sale of these warrants. Taken together, the purchase of the convertible note hedges and the sale of warrants are intended to offset any actual dilution from the conversion of these notes and to effectively increase the overall conversion price from $105.00 to $147.00 per share. As these transactions meet certain accounting criteria, the convertible note hedges and warrants are recorded in stockholders’ equity and will not be subsequently remeasured as long as they continue to meet the conditions for equity classification. The net cost of $17.5 million incurred in connection with the convertible note hedge and warrant transactions was recorded as a reduction to additional paid-in capital on the consolidated balance sheet. In accounting for the issuance of the convertible senior notes, prior to the adoption of ASU 2020-06, the Company separated the 2025 Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar debt instrument that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was determined by deducting the fair value of the liability component from the par value of the 2025 Notes. The equity component was not remeasured as long as it continued to meet the conditions for equity classification. The excess of the principal amount of the liability component over its carrying amount (debt discount) was amortized to interest expense over the term of the 2025 Notes expense at an effective interest rate of 10.2% over the contractual terms of the notes. Upon the adoption of ASU 2020-06 on January 1, 2022, the Company reversed the separation of the debt and equity components and accounted for the 2025 Notes wholly as debt. The Company also reversed the amortization of the debt discount, with a cumulative adjustment to retained earnings on the adoption date. In accounting for the debt issuance costs related to the 2025 Notes, prior to the adoption of ASU 2020-06, the Company allocated the total amount incurred to the liability and equity components of the 2025 Notes based on the same proportion as the accounting for the proceeds from the issuance of the 2025 Notes. Issuance costs attributable to the liability component were to be amortized to interest expense using the effective interest method over the contractual terms of the 2025 Notes. Issuance costs attributable to the equity component were netted with the equity component in stockholders’ equity. Upon the adoption of ASU 2020-06 on January 1, 2022, the Company reversed the allocation of the issuance costs to the equity component and accounted for the entire amount as debt issuance cost to be amortized as interest expense over the remaining term of the 2025 Notes, with a cumulative adjustment to retained earnings on the adoption date. The effective interest rate for the 2025 Notes was 3.5% in the three months ended March 31, 2022 and 10.2% in the three months ended March 31, 2021. The decrease in the effective interest rate is due to the elimination of interest expense related to the conversion feature of the 2025 Notes as a result of adopting ASU 2020-06. See Note 1 for the cumulative effect of the changes made to the consolidated balance sheet as of January 1, 2022 for the adoption of ASU 2020-06. The net carrying amount of the liability component of the 2025 Notes was as follows (in thousands): March 31, December 31, 2022 2021 Principal $ 189,750 $ 189,750 Unamortized discount — (35,079 ) Unamortized issuance cost (3,797 ) (3,361 ) Net carrying amount $ 185,953 $ 151,310 The net carrying amount of the equity component of the 2025 Notes was as follows (in thousands): March 31, December 31, 2022 2021 Debt discount related to value of conversion option $ — $ 49,947 Debt issuance cost — (1,607 ) Net carrying amount $ — $ 48,340 The following table sets forth the interest expense recognized related to the 2021 Notes and the 2025 Notes (in thousands): Three Months Ended March 31, 2022 2021 Contractual interest expense $ 1,305 $ 2,059 Amortization of debt discount — 4,006 Amortization of debt issuance costs 298 481 Total interest expense $ 1,603 $ 6,546 The debt discount associated with the equity component of the 2025 Notes was reversed upon the adoption of ASU 2020-06, which resulted in a decrease in the amount of non-cash interest expense to be recognized after the adoption date of January 1, 2022.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Net Loss Per Share	8. Net Loss Per Share The following table summarizes the computation of basic and diluted net loss per share (in thousands, except share and per share data): Three Months Ended March 31, 2022 2021 Net loss, basic and diluted $ (34,325 ) $ (29,561 ) Weighted average shares used to compute basic and diluted net loss per share 35,073,862 34,633,749 Net loss per share, basic and diluted $ (0.98 ) $ (0.85 ) Basic net loss per share is computed by dividing the net loss by the weighted average number of common shares outstanding for the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of common shares and dilutive common stock equivalents outstanding for the period, if inclusion of these is dilutive. Upon adoption of ASU 2020-06 on January 1, 2022, the Company uses the if-converted method and presumes share settlement for its 2025 Notes when calculating the dilutive effect of these notes. during this period. In connection with the issuance of the 2025 Notes , the Company entered into convertible bond hedges. The convertible bond hedges are not included for purposes of calculating the number of diluted shares outstanding, as their effect would be anti-dilutive. The convertible bond hedges are generally expected, but not guaranteed, to reduce the potential dilution and/or offset the cash payments the Company is required to make upon conversion of the 2025 Notes . Because the Company has reported a net loss for all periods presented, diluted net loss per common share is the same as basic net loss per common share for those periods. The following potentially dilutive securities outstanding at the end of the periods presented have been excluded from the computation of diluted shares outstanding, as the effect would be anti-dilutive: March 31, 2022 2021 Unreleased restricted stock 1,691,713 1,186,059 Options to purchase common stock 688,762 775,956 Convertible senior notes 1,807,141 3,597,174 Warrants related to the issuance of convertible senior notes 1,807,141 3,597,174 Total 5,994,757 9,156,363

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2022
Postemployment Benefits [Abstract]
Employee Benefit Plans	9. Employee Benefit Plans 401(k) Plan In 2007, the Company adopted a 401(k) plan for its employees whereby eligible employees may contribute up to the maximum amount permitted by the Internal Revenue Code. In June 2016, the Company adopted a policy to match a portion of employee contributions for all qualified employees participating in the 401(k) plan. The Company recorded an expense for matching contributions of $2.3 million and $2.2 million for the three months ended March 31, 2022 and 2021, respectively. Employee Stock Purchase Plan The Company’s 2014 Employee Stock Purchase Plan (ESPP) allows eligible employees to purchase shares of the Company’s Class A common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. The ESPP generally provides for six-month There were zero shares of common stock issued under the ESPP for each of the three months ended March 31, 2022 and 2021. Shares available for future purchase under the ESPP were 1,567,514 at March 31, 2022.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying interim condensed consolidated financial statements as of March 31, 2022 and for the three months ended March 31, 2022 and 2021, and the related interim information contained within the notes to the financial statements, are unaudited. The unaudited interim condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (U.S. GAAP) for interim financial information and on the same basis as the audited financial statements included on the Company’s Annual Report on Form 10-K (Annual Report) filed with the Securities and Exchange Commission (SEC) on February 23, 2022. The condensed consolidated financial statements are prepared in U.S. dollars and include the Company’s accounts and those of its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated. In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements contain all adjustments (consisting of normal recurring adjustments) necessary to state fairly the Company’s financial position as of March 31, 2022, and the results of its operations and cash flows for the three months ended March 31, 2022 and 2021. All such adjustments are of a normal and recurring nature. The interim financial data as of March 31, 2022 is not necessarily indicative of the results to be expected for the year ending December 31, 2022, or for any future period. The consolidated balance sheet as of December 31, 2021 was derived from the audited financials as of that date. The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2021 included in the Annual Report.
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Estimates are based on historical experience, where applicable, and other assumptions believed to be reasonable by the management. Actual results may differ from those estimates under different assumptions or conditions. The COVID-19 pandemic h as negatively impacted, and may continue to negatively impact the Company’s operations and revenues and overall financial condition
Foreign Currency Translation	Foreign Currency Translation Unrealized foreign exchange gains and losses from the remeasurement of assets and liabilities denominated in currencies other than the functional currency of the reporting entity are recorded in other income (expense), net. Additionally, realized gains and losses resulting from transactions denominated in currencies other than the local currency are recorded in other income (expense), net in the condensed consolidated statements of operations and comprehensive loss. The Company recorded net unrealized and net realized foreign currency transaction gains (losses) during the periods presented as follows (in thousands): Three Months Ended March 31, 2022 2021 Net unrealized foreign currency gain (loss) $ 166 $ (1,452 ) Net realized foreign currency gain (loss) (75 ) 1,002
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Pronouncements Recently Adopted In August 2020, the FASB issued ASU No. 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (Subtopic 815-40) conversion features as a component of equity. Instead, entities will account for the convertible debt as a single unit of account, unless the conversion feature requires bifurcation and recognition as derivatives. Additionally, the guidance requires entities to use the if-converted method for all convertible instruments in the diluted earnings per share calculation and include the effect of potential share settlement for instruments that may be settled in cash or shares. The Company adopted ASU 2020-06 on January 1, 2022 using the modified retrospective method as of January 1, 2022. The adoption of ASU 2020-06 resulted in an increase of $ 34.3 million to reflect the full principal amount of the 2025 Notes, net of debt issuance costs, a reduction of $ 48.3 million to additional paid-in capital to remove the equity component separately recorded for the conversion features and the debt issuance costs allocated to the conversion feature and a cumulative-effect adjustment of $ 14.0 million reducing the beginning balance of accumulated deficit as of January 1, 2022. Upon the adoption of ASU 2020-06, interest expense is reduced as the Company no longer recognizes any amortization of debt discounts as interest expense, due to the removal of the unamortized debt discounts. In addition, the use of the if-converted method for the 2025 Notes in calculating diluted net income (loss) per share calculation under ASU 2020-06 had no impact to the number of potentially dilutive shares in each of the periods presented. The cumulative effect of the changes made to the consolidated balance sheet as of January 1, 2022 for the adoption of ASU 2020-06 were as follows (in thousands): Balance at Adjustments Due Balance at December 31, 2021 to ASU 2020-06 January 1, 2022 Long term debt $ 151,310 $ 34,345 $ 185,655 Additional paid-in capital $ 928,138 $ (48,340 ) $ 879,798 Accumulated deficit $ (624,193 ) $ 13,995 $ (610,198 )
Significant Accounting Policies	Significant Accounting Policies With the exception of the policies and accounting pronouncements above, there have been no other material changes to the Company’s significant accounting policies from its Annual Report on Form 10-K for the fiscal year ended December 31, 2021.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly-liquid investments purchased with an original maturity of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents include money market funds in the amount of $28.8 million and $9.6 million as of March 31, 2022 and December 31, 2021, respectively. At March 31, 2022 and December 31, 2021, the Company’s cash equivalents were held at institutions in the United States and include deposits in a money market fund which was unrestricted as to withdrawal or use. The Company also held cash in foreign banks of approximately $13.2 million at March 31, 2022 and $8.6 million at December 31, 2021 that was not insured. The Company has not experienced any losses on its deposits of cash and cash equivalents.
Inventories	Inventories Inventories are stated at the lower of cost or net realizable value. Cost is determined using the standard cost method which approximates the first-in, first-out basis. Net realizable value is determined as the prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The Company regularly reviews inventory quantities compared to forecasted sales to record a provision for excess and obsolete inventory when appropriate. Inventory write-downs are recorded for excess and obsolete inventory. The Company estimates forecasted sales by considering product acceptance in the marketplace, customer demand, historical sales, product obsolescence and technological innovations. As a result of these evaluations, the Company recognized total write-downs of $1.1 million and $1.5 million for the three months ended March 31, 2022 and 2021, respectively. T

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Net Unrealized and Net Realized Foreign Currency Transaction Gains (Losses)	The Company recorded net unrealized and net realized foreign currency transaction gains (losses) during the periods presented as follows (in thousands): Three Months Ended March 31, 2022 2021 Net unrealized foreign currency gain (loss) $ 166 $ (1,452 ) Net realized foreign currency gain (loss) (75 ) 1,002
Cumulative Effect Of Changes	The cumulative effect of the changes made to the consolidated balance sheet as of January 1, 2022 for the adoption of ASU 2020-06 were as follows (in thousands): Balance at Adjustments Due Balance at December 31, 2021 to ASU 2020-06 January 1, 2022 Long term debt $ 151,310 $ 34,345 $ 185,655 Additional paid-in capital $ 928,138 $ (48,340 ) $ 879,798 Accumulated deficit $ (624,193 ) $ 13,995 $ (610,198 )

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2022
Revenue From Contract With Customer [Abstract]
Summary of Revenue by Geography on Billing Address of Customer	The following table presents revenue by geography, based on the billing address of the customer (in thousands): Three Months Ended March 31, 2022 2021 United States $ 73,214 $ 74,737 International 14,628 13,873 Total revenue $ 87,842 $ 88,610
Schedule of Revenue by Major Customers by Geographic Area	The United States is the only country that accounts for 10% or more of the revenue during the periods presented: Three Months Ended March 31, 2022 2021 United States 83 % 84 %

Lease Accounting (Tables)

Lease Accounting (Tables)	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Schedule of Weighted Average Lease Terms and Discounts Rates	The weighted average lease terms and discounts rates are as follows: March 31, 2022 December 31, 2021 Operating Lease Term and Discount Rate Weighted-average remaining lease term 3.98 years 4.20 years Weighted-average discount rate 7.0% 7.0%
Schedule of Maturity of Lease Liabilities	As of March 31, 2022, t he maturity of lease liabilities are as follows (in thousands): Operating Leases 2022, remaining months $ 4,345 2023 6,019 2024 6,201 2025 2,849 2026 405 Thereafter 1,978 Total lease payments 21,797 Less: Interest (2,848 ) Present value of lease liabilities $ 18,949
Supplemental Lease Cost Information	Supplemental lease cost information are as follows (in thousands): Three Months Ended March 31, 2022 2021 Operating lease cost $ 1,342 $ 1,234
Schedule Of Operating Lease Assets and Liabilities	Supplemental balance sheet information are as follows (in thousands): March 31, 2022 December 31, 2021 Operating Leases: Operating lease assets $ 16,569 $ 17,577 Other current liabilities $ 4,764 $ 4,588 Long term operating lease liabilities 14,185 15,402 Total operating lease liabilities $ 18,949 $ 19,990
Schedule of Supplemental Cash Flow Information Related to Lease	Supplemental cash flow information are as follows (in thousands): Three Months Ended March 31, 2022 2021 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flow from operating leases $ 1,375 $ 1,248

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Financial Instruments Measured at Fair Value on Recurring Basis	The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): Balance as of March 31, 2022 Level 1 Level 2 Level 3 Total Assets: Money market funds (i) $ 28,796 $ — $ — $ 28,796 Agency bonds (ii) — 32,514 — 32,514 Corporate notes (ii) — 20,196 — 20,196 Treasury bonds (ii) 221,461 — — 221,461 Total assets $ 250,257 $ 52,710 $ — $ 302,967 Balance as of December 31, 2021 Level 1 Level 2 Level 3 Total Assets: Money market funds (i) $ 9,562 $ — $ — $ 9,562 Agency bonds (ii) — 42,538 — 42,538 Commercial paper (ii) — 61,884 — 61,884 Corporate notes (iii) — 30,351 — 30,351 Treasury bonds (ii) 197,552 — — 197,552 Total assets $ 207,114 $ 134,773 $ — $ 341,887 (i) Included in cash and cash equivalents on the condensed consolidated balance sheets. (ii) Included in short-term investments on the condensed consolidated balance sheets. (i i i ) Included in cash and cash equivalents or short-term investments on the condensed consolidated balance sheets.

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2022
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Gross Unrealized Gains and Unrealized Losses of Investment Securities Excluding Investments in Money Market Funds	The following is a summary of the gross unrealized gains and unrealized losses on the Company’s investment securities, excluding investments in money market funds (in thousands): March 31, 2022 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value Investment Securities Agency bonds $ 32,520 $ — $ (6 ) $ 32,514 Corporate notes 20,218 — (22 ) 20,196 Treasury bonds 222,820 — (1,359 ) 221,461 Total securities $ 275,558 $ — $ (1,387 ) $ 274,171 December 31, 2021 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value Investment Securities Agency bonds $ 42,546 $ — $ (8 ) $ 42,538 Commercial paper 61,886 2 (4 ) 61,884 Corporate notes 30,371 — (20 ) 30,351 Treasury bonds 197,889 2 (339 ) 197,552 Total securities $ 332,692 $ 4 $ (371 ) $ 332,325
Summary of Contractual Maturities of Investment Securities	The contractual maturities of the Company’s investment securities as of March 31, 2022 were as follows (in thousands): Amortized Cost Fair Value Amounts maturing within one year $ 253,942 $ 252,830 Amounts maturing after one year through five years 21,616 21,341 Total investment securities $ 275,558 $ 274,171
Components of Inventories	Inventories (in thousands) March 31, December 31, 2022 2021 Raw materials $ 42,079 $ 50,160 Finished goods 48,509 43,357 Total inventories $ 90,588 $ 93,517
Schedule of Property and Equipment, Net and Depreciation and Amortization Expense	Property and Equipment, Net (in thousands) March 31, December 31, 2022 2021 Laboratory equipment $ 10,368 $ 8,722 Computer equipment and software 16,993 16,349 Furniture and fixtures 4,302 4,215 Leasehold improvements 10,562 10,316 Construction in process 2,762 3,717 Total 44,987 43,319 Less: Accumulated depreciation and amortization (24,150 ) (22,655 ) Property and equipment, net $ 20,837 $ 20,664 The Company recognized depreciation and amortization expense on property and equipment as follows (in thousands): Three Months Ended March 31, 2022 2021 Depreciation and amortization expense $ 1,495 $ 1,101
Summary of Accrued Liabilities	Accrued Liabilities (in thousands) March 31, December 31, 2022 2021 Accrued payroll and related expenses $ 26,459 $ 30,957 Accrued professional fees 2,785 6,547 Accrued taxes 1,819 1,074 Accrued clinical and research expenses 241 305 Accrued interest 2,609 1,305 Accrued warranty 452 664 Accrued other 3,961 4,665 Total accrued liabilities $ 38,326 $ 45,517

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2022
Commitments And Contingencies Disclosure [Abstract]
Schedule of Activities Related to Warranty Obligations	Activities related to warranty obligations were as follows (in thousands): Three Months Ended March 31, 2022 2021 Beginning balance $ 664 $ 699 Provision for warranty 715 695 Utilization (927 ) (543 ) Ending balance $ 452 $ 851

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2022
Debt Instrument [Line Items]
Interest Expense Recognized Related to Convertible Notes	The following table sets forth the interest expense recognized related to the 2021 Notes and the 2025 Notes (in thousands): Three Months Ended March 31, 2022 2021 Contractual interest expense $ 1,305 $ 2,059 Amortization of debt discount — 4,006 Amortization of debt issuance costs 298 481 Total interest expense $ 1,603 $ 6,546
2025 Notes and Convertible Notes [Member] | Debt, Liability Component [Member]
Debt Instrument [Line Items]
Net Carrying Amount of Convertible Debt	The net carrying amount of the liability component of the 2025 Notes was as follows (in thousands): March 31, December 31, 2022 2021 Principal $ 189,750 $ 189,750 Unamortized discount — (35,079 ) Unamortized issuance cost (3,797 ) (3,361 ) Net carrying amount $ 185,953 $ 151,310
2025 Notes and Convertible Notes [Member] | Debt, Equity Component [Member]
Debt Instrument [Line Items]
Net Carrying Amount of Convertible Debt	The net carrying amount of the equity component of the 2025 Notes was as follows (in thousands): March 31, December 31, 2022 2021 Debt discount related to value of conversion option $ — $ 49,947 Debt issuance cost — (1,607 ) Net carrying amount $ — $ 48,340

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss per Share	The following table summarizes the computation of basic and diluted net loss per share (in thousands, except share and per share data): Three Months Ended March 31, 2022 2021 Net loss, basic and diluted $ (34,325 ) $ (29,561 ) Weighted average shares used to compute basic and diluted net loss per share 35,073,862 34,633,749 Net loss per share, basic and diluted $ (0.98 ) $ (0.85 )
Computation of Potentially Dilutive Securities Outstanding Excluded from Computation of Diluted Shares	The following potentially dilutive securities outstanding at the end of the periods presented have been excluded from the computation of diluted shares outstanding, as the effect would be anti-dilutive: March 31, 2022 2021 Unreleased restricted stock 1,691,713 1,186,059 Options to purchase common stock 688,762 775,956 Convertible senior notes 1,807,141 3,597,174 Warrants related to the issuance of convertible senior notes 1,807,141 3,597,174 Total 5,994,757 9,156,363

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Net Unrealized and Net Realized Foreign Currency Transaction Gains (Losses) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accounting Policies [Abstract]
Net unrealized foreign currency gain (loss)	$ 166	$ (1,452)
Net realized foreign currency gain (loss)	$ (75)	$ 1,002

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2022	Jan. 01, 2022	Dec. 31, 2021
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit	$ 644,523,000		$ 624,193,000
ASU 2020-06 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption [true false]	true
Accounting standards adopted date	Jan. 1, 2022
Reduction of additional paid-in-capital	$ 48,300,000
Accumulated deficit		$ 610,198,000
Amortization of debt discounts as interest expense	0
ASU 2020-06 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit	14,000,000
ASU 2020-06 [Member] | 2025 Notes [Member]
Summary Of Significant Accounting Policies [Line Items]
Increase in notes principal amount	$ 34,300,000

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Cumulative Effect Of Changes (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Jan. 01, 2022	Dec. 31, 2021
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Long-term debt	$ 185,953		$ 151,310
Additional paid-in capital	886,451		928,138
Accumulated deficit	$ (644,523)		(624,193)
ASU 2020-06 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Long-term debt		$ 185,655
Additional paid-in capital		879,798
Accumulated deficit		(610,198)
Scenario Previously Reported [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Long-term debt			151,310
Additional paid-in capital			928,138
Accumulated deficit			$ (624,193)
Restatement Adjustment [Member] | ASU 2020-06 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Long-term debt		34,345
Additional paid-in capital		(48,340)
Accumulated deficit		$ 13,995

Revenue - Summary of Revenue by

Revenue - Summary of Revenue by Geography on Billing Address of Customer (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation Of Revenue [Line Items]
Total revenue	$ 87,842	$ 88,610
United States [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	73,214	74,737
International [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	$ 14,628	$ 13,873

Revenue - Schedule of Revenue b

Revenue - Schedule of Revenue by Major Customers by Geographic Area (Detail)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenue Benchmark | Geographic Concentration Risk [Member] | United States [Member]
Concentration Risk [Line Items]
Revenue	83.00%	84.00%

Revenue - Additional Informatio

Revenue - Additional Information (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022USD ($)Customer	Mar. 31, 2021USD ($)Customer	Dec. 31, 2021Customer
Disaggregation Of Revenue [Line Items]
Recovery of bad debt expenses	$ 100	$ 100
Revenue	87,842	$ 88,610
Painful Diabetic Neuropathy [Member]
Disaggregation Of Revenue [Line Items]
Revenue	$ 6,000
Percentage of permanent implant procedures	7.00%
Customer Concentration Risk [Member] | Revenue Benchmark | Major Customers [Member]
Disaggregation Of Revenue [Line Items]
Concentration risk, percentage	10.00%	10.00%
Number of customers accounted 10% or more concentration risk | Customer	0	0
Credit Concentration Risk [Member] | Accounts Receivable [Member] | Major Customers [Member]
Disaggregation Of Revenue [Line Items]
Concentration risk, percentage	10.00%		10.00%
Number of customers accounted 10% or more concentration risk | Customer	0		0

Lease Accounting - Schedule of

Lease Accounting - Schedule of Weighted Average Lease Terms and Discounts Rates (Detail)	Mar. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Weighted-average remaining lease term	3 years 11 months 23 days	4 years 2 months 12 days
Weighted-average discount rate	7.00%	7.00%

Lease Accounting - Schedule o_2

Lease Accounting - Schedule of Maturity of Lease Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Apr. 30, 2021
Leases [Abstract]
2022, remaining months	$ 4,345
2023	6,019
2024	6,201
2025	2,849
2026	405
Thereafter	1,978
Total lease payments	21,797
Less: Interest	(2,848)
Present value of lease liabilities	$ 18,949	$ 19,990	$ 2,900

Lease Accounting - Supplemental

Lease Accounting - Supplemental Lease Cost Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Leases [Abstract]
Operating lease cost	$ 1,342	$ 1,234

Lease Accounting - Summary of O

Lease Accounting - Summary of Operating Lease Assets and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Apr. 30, 2021
Operating Leases:
Operating lease assets	$ 16,569	$ 17,577	$ 2,900
Other current liabilities	$ 4,764	$ 4,588
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other current liabilities	Other current liabilities
Long term operating lease liabilities	$ 14,185	$ 15,402
Total operating lease liabilities	$ 18,949	$ 19,990	$ 2,900

Lease Accounting - Schedule o_3

Lease Accounting - Schedule of Supplemental Cash Flow Information Related to Lease (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flow from operating leases	$ 1,375	$ 1,248

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments Measured at Fair Value on Recurring Basis (Detail) - Fair Value Measurements Recurring [Member] - USD ($) $ in Thousands		Mar. 31, 2022		Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		$ 302,967		$ 341,887
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		250,257		207,114
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		52,710		134,773
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	[1]	28,796		9,562
Money Market Funds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	[1]	28,796		9,562
Agency Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	[2]	32,514		42,538
Agency Bonds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	[2]	32,514		42,538
Corporate Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		20,196	[2]	30,351	[3]
Corporate Notes [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		20,196	[2]	30,351	[3]
Treasury Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	[2]	221,461		197,552
Treasury Bonds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	[2]	$ 221,461		197,552
Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	[2]			61,884
Commercial Paper [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	[2]			$ 61,884
[1]	Included in cash and cash equivalents on the condensed consolidated balance sheets.
[2]	Included in short-term investments on the condensed consolidated balance sheets.
[3]	Included in cash and cash equivalents or short-term investments on the condensed consolidated balance sheets.

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - 2.75% Convertible Senior Notes due 2025 [Member] - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, interest rate	2.75%	2.75%
Debt instrument due year	2025	2025
Fair Value of Notes	$ 204	$ 212

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Investments Debt And Equity Securities [Abstract]
Money market funds	$ 28.8		$ 9.6
Cash held in foreign banks	13.2		$ 8.6
Write down of inventory	$ 1.1	$ 1.5

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Gross Unrealized Gains and Unrealized Losses of Investment Securities Excluding Investments in Money Market Funds (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 275,558	$ 332,692
Gross Unrealized Holding Gains		4
Gross Unrealized Holding Losses	(1,387)	(371)
Aggregate Fair Value	274,171	332,325
Agency Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	32,520	42,546
Gross Unrealized Holding Losses	(6)	(8)
Aggregate Fair Value	32,514	42,538
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		61,886
Gross Unrealized Holding Gains		2
Gross Unrealized Holding Losses		(4)
Aggregate Fair Value		61,884
Corporate Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20,218	30,371
Gross Unrealized Holding Losses	(22)	(20)
Aggregate Fair Value	20,196	30,351
Treasury Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	222,820	197,889
Gross Unrealized Holding Gains		2
Gross Unrealized Holding Losses	(1,359)	(339)
Aggregate Fair Value	$ 221,461	$ 197,552

Balance Sheet Components - Su_2

Balance Sheet Components - Summary of Contractual Maturities of Investment Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Investments Debt And Equity Securities [Abstract]
Amortized Cost, Amounts maturing within one year	$ 253,942
Amortized Cost, Amounts maturing after one year through five years	21,616
Amortized Cost	275,558	$ 332,692
Fair Value, Amounts maturing within one year	252,830
Fair Value, Amounts maturing after one year through five years	21,341
Fair Value, Total investment securities	$ 274,171	$ 332,325

Balance Sheet Components - Comp

Balance Sheet Components - Components of Inventories (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Inventory Disclosure [Abstract]
Raw materials	$ 42,079	$ 50,160
Finished goods	48,509	43,357
Total inventories	$ 90,588	$ 93,517

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 44,987	$ 43,319
Less: Accumulated depreciation and amortization	(24,150)	(22,655)
Property and equipment, net	20,837	20,664
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	10,368	8,722
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	16,993	16,349
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,302	4,215
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	10,562	10,316
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 2,762	$ 3,717

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Property and Equipment, Depreciation and Amortization Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 1,495	$ 1,101

Balance Sheet Components - Su_3

Balance Sheet Components - Summary of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued payroll and related expenses	$ 26,459	$ 30,957
Accrued professional fees	2,785	6,547
Accrued taxes	1,819	1,074
Accrued clinical and research expenses	241	305
Accrued interest	2,609	1,305
Accrued warranty	452	664	$ 851	$ 699
Accrued other	3,961	4,665
Total accrued liabilities	$ 38,326	$ 45,517

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Nov. 01, 2021USD ($)	Oct. 31, 2021USD ($)	Aug. 31, 2020USD ($)ft²	Dec. 31, 2016USD ($)ft²	Mar. 31, 2015USD ($)ft²	Mar. 31, 2022USD ($)	Dec. 31, 2021USD ($)	Sep. 30, 2021USD ($)	Apr. 30, 2021USD ($)	Apr. 27, 2018Patent	Dec. 09, 2016Patent
Other Commitments [Line Items]
Operating lease assets						$ 16,569,000	$ 17,577,000		$ 2,900,000
Operating lease Liabilities						$ 18,949,000	19,990,000		$ 2,900,000
Standard product warranty, description						limited one- to five-year warranty
Contingent liabilities						$ 20,000,000	20,000,000	$ 20,000,000
Other contingent liabilities						0	$ 0
Patent Infringement [Member]
Other Commitments [Line Items]
Contingent liabilities						$ 20,000,000
Boston Scientific Corporation [Member]
Other Commitments [Line Items]
Patent infringement lawsuit allegation against number of patents | Patent										9	10
Amount awarded by jury	$ 20,000,000
Costa Rica [Member]
Other Commitments [Line Items]
Lease agreement, commencement period			2020-08
Area of office space | ft²			35,411
Lease agreement, effective date			Apr. 30, 2021
Lease agreement, expiration date			Jun. 30, 2031
Lease agreement, lease expense			$ 3,900,000
Redwood Office Agreement [Member]
Other Commitments [Line Items]
Lease agreement, commencement period						2015-03
Area of office space | ft²					50,000
Lease agreement, effective date					Jun. 30, 2015
Lease agreement, expiration period					2022-05
Lease expense, payment due					$ 2,000,000
Annual lease expense payable in final year of lease term					$ 2,400,000
Redwood Office Agreement Additional Expansion Premises [Member] | Amendment 1 [Member]
Other Commitments [Line Items]
Area of office space | ft²				50,000
Lease expense, payment due				$ 1,200,000
Annual lease expense payable in final year of lease term				$ 2,900,000
Commencement date description						The lease for the Expansion Premises commenced on June 1, 2018
Lease commencement date				Jun. 1, 2018
Lease agreement, expiration date				May 31, 2025
Non-cancellable Facility Lease [Member]
Other Commitments [Line Items]
Lease agreement, effective date						Mar. 1, 2017
Lease agreement, expiration date						Feb. 28, 2022
Lease agreement, lease expense						$ 400,000
Non-cancellable Facility Lease [Member] | Amendment 1 [Member]
Other Commitments [Line Items]
Lease agreement, expiration date		May 31, 2025
Lease agreement, lease expense		$ 400,000

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Activities Related to Warranty Obligations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Beginning balance	$ 664	$ 699
Provision for warranty	715	695
Utilization	(927)	(543)
Ending balance	$ 452	$ 851

Debt - Additional Information (

Debt - Additional Information (Detail)	Jun. 01, 2021USD ($)shares	Apr. 30, 2020USD ($)d$ / sharesshares	Mar. 31, 2022USD ($)	Dec. 31, 2021USD ($)	Mar. 31, 2021
2021 Notes and Convertible Notes [Member] | Debt, Liability Component [Member]
Debt Instrument [Line Items]
Principal amount	$ 172,500,000
Convertible notes, shares issued | shares	682,912
Share received on option exercise | shares	682,916
2025 Notes and Convertible Notes [Member]
Debt Instrument [Line Items]
Convertible notes, shares issued | shares		9.5238
Aggregate principal amount of convertible senior notes		$ 165,000,000
Debt instrument, interest rate		2.75%
Debt instrument due year		2025
Additional aggregate principal amount of convertible senior notes		$ 24,800,000
Debt instrument frequency of payment			semi-annually in arrears on April 1 and October 1 of each year, commencing on October 1, 2020
Net proceeds from the debt offering after deducting transaction costs		183,600,000
Convertible notes principal amount		$ 1,000
Convertible notes, type of equity security issued			common stock
Convertible notes, conversion price | $ / shares		$ 105
Debt instrument convertible, percentage of conversion price		130.00%
Percentage of repurchase price, which is equal to principal amount of convertible notes		100.00%
Converted Value in Excess of Principal			$ 0
Number of shares purchased under convertible note hedge transactions | shares		1,800,000
Purchase price of the shares issued under convertible note hedge transactions | $ / shares		$ 105
Total cost of the convertible note hedge transactions		$ 52,400,000
Proceeds from issuance of warrants		34,900,000
Net cost of reduction to additional paid-in capital		$ 17,500,000
Debt instrument, effective interest rate		10.20%	3.50%		10.20%
2025 Notes and Convertible Notes [Member] | Warrant [Member]
Debt Instrument [Line Items]
Number of shares issued for warrants under convertible note hedge transactions | shares		1,800,000
Purchase price of the shares issued under convertible note hedge transactions | $ / shares		$ 147
2025 Notes and Convertible Notes [Member] | 130% for Applicable Conversion Price [Member]
Debt Instrument [Line Items]
Debt instrument convertible trading days | d		20
Debt instrument convertible consecutive trading days | d		30
2025 Notes and Convertible Notes [Member] | 98% Applicable Conversion Price [Member]
Debt Instrument [Line Items]
Debt instrument convertible trading days | d		5
Debt instrument convertible consecutive trading days | d		10
2025 Notes and Convertible Notes [Member] | Minimum [Member] | Warrant [Member]
Debt Instrument [Line Items]
Overall conversion price | $ / shares		$ 105
2025 Notes and Convertible Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Percentage of closing sale price of common stock		98.00%
2025 Notes and Convertible Notes [Member] | Maximum [Member] | Warrant [Member]
Debt Instrument [Line Items]
Overall conversion price | $ / shares		$ 147
2025 Notes and Convertible Notes [Member] | Debt, Liability Component [Member]
Debt Instrument [Line Items]
Principal amount			$ 189,750,000	$ 189,750,000

Debt - Net Carrying Amount of L

Debt - Net Carrying Amount of Liability Component of Convertible Debt (Detail) - 2025 Notes and Convertible Notes [Member] - Debt, Liability Component [Member] - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Principal	$ 189,750	$ 189,750
Unamortized discount		(35,079)
Unamortized issuance cost	(3,797)	(3,361)
Net carrying amount	$ 185,953	$ 151,310

Debt - Net Carrying Amount of E

Debt - Net Carrying Amount of Equity Component of Convertible Debt (Detail) - 2025 Notes and Convertible Notes [Member] - Debt, Equity Component [Member] $ in Thousands	Dec. 31, 2021USD ($)
Debt Instrument [Line Items]
Debt discount related to value of conversion option	$ 49,947
Debt issuance cost	(1,607)
Net carrying amount	$ 48,340

Debt - Interest Expense Recogni

Debt - Interest Expense Recognized Related to Convertible Notes (Detail) - 2021 Notes and 2025 Notes [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Debt Instrument [Line Items]
Contractual interest expense	$ 1,305	$ 2,059
Amortization of debt discounts as interest expense		4,006
Amortization of debt issuance costs	298	481
Total interest expense	$ 1,603	$ 6,546

Net Loss Per Share - Computatio

Net Loss Per Share - Computation of Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share [Abstract]
Net loss, basic and diluted	$ (34,325)	$ (29,561)
Weighted average shares used to compute basic and diluted net loss per share	35,073,862	34,633,749
Net loss per share, basic and diluted	$ (0.98)	$ (0.85)

Net Loss Per Share - Computat_2

Net Loss Per Share - Computation of Potentially Dilutive Securities Outstanding Excluded from Computation of Diluted Shares (Detail) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted shares outstanding	5,994,757	9,156,363
Unreleased Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted shares outstanding	1,691,713	1,186,059
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted shares outstanding	688,762	775,956
Convertible Senior Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted shares outstanding	1,807,141	3,597,174
Warrants Related to the Issuance of Convertible Senior Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted shares outstanding	1,807,141	3,597,174

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense for matching contributions	$ 2.3	$ 2.2
ESPP offering period	6 months
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum employee subscription rate	15.00%
Purchase price of common stock shares, lower of fair market value, percentage	85.00%
Shares of common stock issued	0	0
Shares available for future purchase	1,567,514