Ultragenyx Pharmaceutical (RARE) 10-Q 2 Nov 22 2022 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2022	Oct. 28, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Trading Symbol	RARE
Entity Registrant Name	ULTRAGENYX PHARMACEUTICAL INC.
Entity Central Index Key	0001515673
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		70,105,654
Entity Shell Company	false
Entity File Number	001-36276
Entity Tax Identification Number	27-2546083
Entity Address, Address Line One	60 Leveroni Court
Entity Address, City or Town	Novato
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94949
City Area Code	415
Local Phone Number	483-8800
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.001 par value
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 391,651	$ 307,584
Marketable debt securities	497,024	432,612
Accounts receivable, net	31,164	28,432
Inventory	21,849	16,231
Prepaid expenses and other current assets	70,980	71,745
Total current assets	1,012,668	856,604
Property, plant, and equipment, net	234,614	141,247
Equity investments	13,786	34,925
Marketable debt securities	107,563	258,933
Right-of-use assets	28,751	34,936
Intangible assets, net	158,401	130,788
Goodwill	44,406	44,406
Other assets	18,285	20,558
Total assets	1,618,474	1,522,397
Current liabilities:
Accounts payable	23,533	17,138
Accrued liabilities	189,051	145,555
Contract liabilities	2,958	7,609
Lease liabilities	11,819	11,066
Total current liabilities	227,361	181,368
Lease liabilities	22,865	30,904
Contract liabilities	0	1,467
Deferred tax liabilities	33,306	33,306
Liabilities related to the sale of future royalties	862,063	351,786
Other liabilities	4,050	1,005
Total liabilities	1,149,645	599,836
Stockholders’ equity:
Preferred stock -25,000,000 shares authorized; nil outstanding as of September 30, 2022 and December 31, 2021	0	0
Common stock - 250,000,000 shares authorized; 70,079,777 and 69,344,998 shares issued and outstanding as of September 30, 2022 and December 31, 2021, respectively	70	69
Additional paid-in capital	3,108,170	2,997,497
Accumulated other comprehensive loss	(10,222)	(1,404)
Accumulated deficit	(2,629,189)	(2,073,601)
Total stockholders’ equity	468,829	922,561
Total liabilities and stockholders’ equity	$ 1,618,474	$ 1,522,397

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares	Sep. 30, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	70,079,777	69,344,998
Common stock, shares outstanding	70,079,777	69,344,998

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenues:
Total revenues	$ 90,703	$ 81,647	$ 259,981	$ 268,017
Operating expenses:
Cost of sales	8,631	4,175	23,001	12,499
Research and development	237,297	113,417	534,981	374,140
Selling, general and administrative	69,841	53,883	205,290	160,551
Total operating expenses	315,769	171,475	763,272	547,190
Loss from operations	(225,066)	(89,828)	(503,291)	(279,173)
Interest income	3,483	408	4,876	1,488
Change in fair value of equity investments	(1,626)	25,702	(21,139)	(25,963)
Non-cash interest expense on liabilities related to the sale of future royalties	(14,505)	(8,683)	(27,141)	(25,618)
Other expense	(1,105)	(415)	(1,746)	(1,277)
Loss before income taxes	(238,819)	(72,816)	(548,441)	(330,543)
Provision for income taxes	(6,287)	(182)	(7,147)	(1,024)
Net loss	$ (245,106)	$ (72,998)	$ (555,588)	$ (331,567)
Earnings Per Share, Basic	$ (3.50)	$ (1.08)	$ (7.96)	$ (4.91)
Earnings Per Share, Diluted	$ (3.50)	$ (1.08)	$ (7.96)	$ (4.91)
Weighted Average Number of Shares Outstanding, Basic	70,054,173	67,875,363	69,834,037	67,533,671
Weighted Average Number of Shares Outstanding, Diluted	70,054,173	67,875,363	69,834,037	67,533,671
Collaboration and License
Revenues:
Total revenues	$ 52,827	$ 55,048	$ 154,328	$ 197,998
Product Sales
Revenues:
Total revenues	32,503	21,950	90,019	56,809
Non-cash Collaboration Royalty Revenue
Revenues:
Total revenues	$ 5,373	$ 4,649	$ 15,634	$ 13,210

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net loss	$ (245,106)	$ (72,998)	$ (555,588)	$ (331,567)
Other comprehensive loss:
Foreign currency translation adjustments	(420)	(166)	(1,211)	(348)
Unrealized loss on available-for-sale securities	(888)	(12)	(7,607)	(287)
Other comprehensive loss:	(1,308)	(178)	(8,818)	(635)
Total comprehensive loss	$ (246,414)	$ (73,176)	$ (564,406)	$ (332,202)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2020	$ 1,154,375	$ 67	$ 2,773,195	$ 689	$ (1,619,576)
Beginning balance, shares at Dec. 31, 2020		66,818,520
Stock-based compensation	78,324		78,324
Issuance of common stock under equity plan awards, net of tax	33,177	$ 1	33,176
Issuance of common stock under equity plan awards, net of tax, shares		1,143,443
Other comprehensive income (loss)	(635)			(635)
Net loss	(331,567)				(331,567)
Ending balance at Sep. 30, 2021	933,674	$ 68	2,884,695	54	(1,951,143)
Ending balance, shares at Sep. 30, 2021		67,961,963
Beginning balance at Jun. 30, 2021	972,171	$ 68	2,850,016	232	(1,878,145)
Beginning balance, shares at Jun. 30, 2021		67,764,950
Stock-based compensation	27,005		27,005
Issuance of common stock under equity plan awards, net of tax	7,674	$ 0	7,674
Issuance of common stock under equity plan awards, net of tax, shares		197,013
Other comprehensive income (loss)	(178)			(178)
Net loss	(72,998)				(72,998)
Ending balance at Sep. 30, 2021	933,674	$ 68	2,884,695	54	(1,951,143)
Ending balance, shares at Sep. 30, 2021		67,961,963
Beginning balance at Dec. 31, 2021	$ 922,561	$ 69	2,997,497	(1,404)	(2,073,601)
Beginning balance, shares at Dec. 31, 2021	69,344,998	69,344,998
Issuance of common stock in connection with at-the-market offering, net of issuance costs, shares	1,050,372
Stock-based compensation	$ 101,862		101,862
Issuance of common stock under equity plan awards, net of tax	8,812	$ 1	8,811
Issuance of common stock under equity plan awards, net of tax, shares		734,779
Other comprehensive income (loss)	(8,818)			(8,818)
Net loss	(555,588)				(555,588)
Ending balance at Sep. 30, 2022	$ 468,829	$ 70	3,108,170	(10,222)	(2,629,189)
Ending balance, shares at Sep. 30, 2022	70,079,777	70,079,777
Beginning balance at Jun. 30, 2022	$ 678,073	$ 70	3,071,000	(8,914)	(2,384,083)
Beginning balance, shares at Jun. 30, 2022		70,010,398
Stock-based compensation	36,096		36,096
Issuance of common stock under equity plan awards, net of tax	1,074		1,074
Issuance of common stock under equity plan awards, net of tax, shares		69,379
Other comprehensive income (loss)	(1,308)			(1,308)
Net loss	(245,106)				(245,106)
Ending balance at Sep. 30, 2022	$ 468,829	$ 70	$ 3,108,170	$ (10,222)	$ (2,629,189)
Ending balance, shares at Sep. 30, 2022	70,079,777	70,079,777

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Operating activities:
Net loss	$ (555,588)	$ (331,567)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	101,022	78,133
Acquired in-process research and development	75,234	0
Amortization of premium on marketable debt securities, net	4,349	4,499
Depreciation and amortization	13,263	9,705
Change in fair value of equity investments	21,139	25,963
Non-cash collaboration royalty revenue	(15,634)	(13,210)
Non-cash interest expense on liabilities related to the sale of future royalties	27,141	25,618
Other	564	433
Changes in operating assets and liabilities:
Accounts receivable	(2,973)	(2,362)
Inventory	(5,496)	(2,127)
Prepaid expenses and other assets	558	(6,979)
Accounts payable, accrued, and other liabilities	52,416	1,920
Contract liabilities	(6,118)	(74,377)
Net cash used in operating activities	(290,123)	(284,351)
Investing activities:
Purchase of property, plant, and equipment	(89,153)	(57,045)
Acquisition, net of cash acquired	(75,391)	0
Purchase of marketable debt securities	(416,161)	(917,409)
Proceeds from sale of marketable debt securities	82,966	83,318
Proceeds from maturities of marketable debt securities	407,926	583,997
Proceeds from sale of equity investments	0	43,197
Payment for intangible asset	(30,000)	0
Other	(240)	(487)
Net cash used in investing activities	(120,053)	(264,429)
Financing activities:
Proceeds from sale of future royalties, net	490,950	0
Proceeds from the issuance of common stock equity plan awards, net	8,812	33,177
Other	(436)	(350)
Net cash provided by financing activities	499,326	32,827
Effect of exchange rate changes on cash	(2,427)	(802)
Net increase (decrease) in cash, cash equivalents and restricted cash	86,723	(516,755)
Cash, cash equivalents and restricted cash at beginning of period	309,585	726,294
Cash, cash equivalents and restricted cash at end of period	396,308	209,539
Supplemental disclosures of non-cash information:
Acquired lease liabilities arising from obtaining right-of-use assets	1,168	2,610
Non-cash interest expense on liability related to the sale of future royalties capitalized into ending property, plant and equipment	$ 7,820	$ 0

Organization

Organization	9 Months Ended
	Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1. Organization Ultragenyx Pharmaceutical Inc. (the Company) is a biopharmaceutical company incorporated in Delaware. The Company is focused on the identification, acquisition, development, and commercialization of novel products for the treatment of serious rare and ultra-rare genetic diseases. The Company operates as one reportable segment. The Company has four commercially approved products. Crysvita® (burosumab) is approved in the United States (U.S.) by the U.S. Food and Drug Administration (FDA) and Canada for the treatment of X-linked hypophosphatemia (XLH) in adult and pediatric patients one year of age and older, and is approved in the European Union (EU) and the United Kingdom (U.K.), for the treatment of XLH with radiographic evidence of bone disease in children one year of age and older, adolescents, and adults. In Brazil, Colombia, Mexico, Chile, Peru, and Argentina, Crysvita is approved for treatment of XLH in adult and pediatric patients one year of age and older. Crysvita is also approved in the U.S. by the FDA and in Canada and Peru for the treatment of fibroblast growth factor 23 (FGF23)-related hypophosphatemia in tumor-induced osteomalacia (TIO), associated with phosphaturic mesenchymal tumors that cannot be curatively resected or localized in adults and pediatric patients 2 years of age and older. Mepsevii® (vestronidase alfa) is approved by the FDA as the first medicine for the treatment of children and adults with mucopolysaccharidosis VII (MPS VII), also known as Sly syndrome. In the EU and the U.K., Mepsevii is approved under exceptional circumstances for patients of all ages for the treatment of non-neurological manifestations of MPS VII. In Brazil, Mexico, and Japan Mepsevii is approved for the treatment of MPS VII for patients of all ages. Dojolvi® (triheptanoin) is approved in the U.S., Canada, and Brazil for the treatment of pediatric and adult patients severely affected by long-chain fatty acid oxidation disorders (LC-FAOD). Evkeeza® (evinacumab) is approved in the U.S. and the European Economic Area (EEA) for the treatment of homozygous familial hypercholesterolemia (HoFH). In January 2022, the Company licensed exclusive rights from Regeneron Pharmaceuticals (Regeneron) to commercialize Evkeeza® (evinacumab) outside of the U.S. The Company also has the following ongoing clinical development programs: • UX111 (formerly ABO-102) is an AAV9 gene therapy product candidate for the treatment of patients with Sanfilippo syndrome type A (MPS IIIA), a rare lysosomal storage disease. In May 2022, the Company announced an exclusive license agreement with Abeona Therapeutics Inc. (Abeona) for UX111 whereby the Company assumed responsibility for the UX111 program, as further described in Note 7; • DTX401 is an adeno-associated virus 8 (AAV8) gene therapy product candidate for the treatment of patients with glycogen storage disease type Ia (GSDIa); • DTX301 is an AAV8 gene therapy product candidate in development for the treatment of patients with ornithine transcarbamylase (OTC) deficiency, the most common urea cycle disorder; • UX143 (setrusumab), which is subject to the Company ’ s collaboration agreement with Mereo BioPharma 3 (Mereo), is a fully human monoclonal antibody that inhibits sclerostin, a protein that acts on a key bone-signaling pathway and inhibits the activity of bone-forming cells for the treatment of patients with osteogenesis imperfect (OI); • GTX-102 is an antisense oligonucleotide (ASO), which the Company is developing through GeneTx Biotherapeutics LLC (GeneTx) for the treatment of Angelman syndrome, a debilitating and rare neurogenetic disorder caused by loss-of-function of the maternally inherited allele of the UBE3A gene. In July 2022, the Company executed its option to acquire GeneTx as further described in Note 6; • UX701 is an adeno-associated virus 9, (AAV9) gene therapy designed to deliver stable expression of a truncated version of the ATP7B copper transporter following a single intravenous infusion to improve copper distribution and excretion from the body and reverse pathological findings of Wilson liver disease; and • UX053 is a messenger RNA (mRNA) product candidate designed for the treatment of patients with Glycogen Storage Disease Type III (GSDIII), a disease caused by a glycogen debranching enzyme (AGL) deficiency that results in glycogen accumulation in the liver and muscle. The Company has sustained operating losses and expects such annual losses to continue over the next several years. The Company ’ s ultimate success depends on the outcome of its research and development and commercialization activities. Management recognizes that the Company will likely need to raise additional capital to fully implement its business plans. Through September 30, 2022, the Company has relied primarily on its sale of equity securities, its revenues from commercial products, its sale of future royalties, and strategic collaboration arrangements to finance its operations. The Company expects it will need to raise additional capital through the issuance of equity, borrowings, or strategic alliances with partner companies. However, if such financing is not available at adequate levels, the Company would need to reevaluate its operating plans.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries and have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information and in accordance with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. The unaudited interim Condensed Consolidated Financial Statements have been prepared on the same basis as the annual financial statements. In the opinion of management, the accompanying unaudited Condensed Consolidated Financial Statements reflect all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation. These financial statements should be read in conjunction with the audited financial statements and notes thereto for the preceding fiscal year contained in the Company’s Annual Report on Form 10-K filed on February 15, 2022 (Annual Report) with the U.S. Securities and Exchange Commission (the SEC). The results of operations for the three and nine months ended September 30, 2022 are not necessarily indicative of the results to be expected for the year ending December 31, 2022. The Condensed Consolidated Balance Sheet as of December 31, 2021 has been derived from audited financial statements at that date, but does not include all of the information required by GAAP for complete financial statements. Use of Estimates The accompanying Condensed Consolidated Financial Statements have been prepared in accordance with GAAP. The preparation of the Condensed Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities and the reported amounts of expenses in the Condensed Consolidated Financial Statements and the accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to clinical trial accruals, fair value of assets and liabilities, income taxes, stock-based compensation, revenue recognition, and liabilities related to the sale of future royalties. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates. Cash, Cash Equivalents and Restricted Cash Restricted cash primarily consists of money market accounts used as collateral for the Company’s obligations under its facility leases. The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the Condensed Consolidated Balance Sheets that sum to the total of the same such amounts shown in the Condensed Consolidated Statement of Cash Flows (in thousands): September 30, 2022 2021 Cash and cash equivalents $ 391,651 $ 197,538 Restricted cash included in prepaid expenses and 517 10,000 Restricted cash included in other assets 4,140 2,001 Total cash, cash equivalents, and restricted cash $ 396,308 $ 209,539 Credit Losses The Company is exposed to credit losses primarily through receivables from customers and collaborators and through its available-for-sale debt securities. For trade receivables and other instruments, the Company uses a forward-looking expected loss model that generally results in the earlier recognition of allowances for losses. For available-for-sale debt securities with unrealized losses, the losses are recognized as allowances rather than as reductions in the amortized cost of the securities. The Company’s expected loss allowance methodology for the receivables is developed using historical collection experience, current and future economic market conditions, a review of the current aging status and financial condition of the entities. Specific allowance amounts are established to record the appropriate allowance for customers that have a higher probability of default. Balances are written off when determined to be uncollectible. The Company’s expected loss allowance methodology for the debt securities is developed by reviewing the extent of the unrealized loss, the size, term, geographical location, and industry of the issuer, the issuers’ credit ratings and any changes in those ratings, as well as reviewing current and future economic market conditions and the issuers’ current status and financial condition. There were no material credit losses recorded for receivables and available-for-sale debt securities for the three and nine months ended September 30, 2022 and 2021. Revenue Recognition Collaboration and license revenue The Company has certain license and collaboration agreements that are within the scope of Accounting Standards Codification (ASC) 808, Collaborative Agreements , which provides guidance on the presentation and disclosure of collaborative arrangements. Generally, the classification of the transactions under the collaborative arrangements is determined based on the nature of contractual terms of the arrangement, along with the nature of the operations of the participants. The Company records its share of collaboration revenue, net of transfer pricing related to net sales in the period in which such sales occur, if the Company is considered as an agent in the arrangement. The Company is considered an agent when the collaboration partner controls the product before transfer to the customers and has the ability to direct the use of and obtain substantially all of the remaining benefits from the product. Funding received related to research and development services and commercialization costs is generally classified as a reduction of research and development expenses and selling, general and administrative expenses, respectively, in the Condensed Consolidated Statement of Operations, because the provision of such services for collaborative partners are not considered to be part of the Company’s ongoing major or central operations. In order to record collaboration revenue, the Company utilizes certain information from its collaboration partners, including revenue from the sale of the product, associated reserves on revenue, and costs incurred for development and sales activities. For the periods covered in the financial statements presented, there have been no material changes to prior period estimates of revenues and expenses. The Company sold the right to receive certain royalty payments from net sales of Crysvita in certain territories to RPI Finance Trust (RPI), an affiliate of Royalty Pharma, and to OCM LS23 Holdings LP, an investment vehicle for Ontario Municipal Employees Retirement System (OMERS) as further described in Note 8. The Company records the royalty revenue from the net sales of Crysvita in the applicable territories on a prospective basis as non-cash royalty revenue in the Condensed Consolidated Statements of Operations over the term of the applicable arrangement. The terms of the Company’s collaboration and license agreements may contain multiple performance obligations, which may include licenses and research and development activities. The Company evaluates these agreements under ASC 606, Revenue from Contracts with Customers (ASC 606), to determine the distinct performance obligations. The Company analogizes to ASC 606 for the accounting for distinct performance obligations for which there is a customer relationship. Prior to recognizing revenue, the Company makes estimates of the transaction price, including variable consideration that is subject to a constraint. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. Total consideration may include nonrefundable upfront license fees, payments for research and development activities, reimbursement of certain third-party costs, payments based upon the achievement of specified milestones, and royalty payments based on product sales derived from the collaboration. If there are multiple distinct performance obligations, the Company allocates the transaction price to each distinct performance obligation based on its relative standalone selling price. The standalone selling price is generally determined based on the prices charged to customers or using expected cost-plus margin. The Company estimates the efforts needed to complete the performance obligations and recognizes revenue by measuring the progress towards complete satisfaction of the performance obligations using input measures. Product sales The Company sells its approved products through a limited number of distributors. Under ASC 606, revenue from product sales is recognized at the point in time when the delivery is made and when title and risk of loss transfers to these distributors. The Company also recognizes revenue from sales of certain products on a “named patient” basis, which are allowed in certain countries prior to the commercial approval of the product. Prior to recognizing revenue, the Company makes estimates of the transaction price, including any variable consideration that is subject to a constraint. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. Product sales are recorded net of estimated government-mandated rebates and chargebacks, estimated product returns, and other deductions. Provisions for returns and other adjustments are provided for in the period the related revenue is recorded, as estimated by management. These reserves are based on estimates of the amounts earned or to be claimed on the related sales and are reviewed periodically and adjusted as necessary. The Company’s estimates of government mandated rebates, chargebacks, estimated product returns, and other deductions depends on the identification of key customer contract terms and conditions, as well as estimates of sales volumes to different classes of payors. If actual results vary, the Company may need to adjust these estimates, which could have an effect on earnings in the period of the adjustment.

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Financial Instruments	3. Financial Instruments Financial assets and liabilities are recorded at fair value. The carrying amount of certain financial instruments, including cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate fair value due to their relatively short maturities. Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1 —Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2 —Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level 3 —Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data. The Company determines the fair value of its equity investments in Arcturus Therapeutics Holdings Inc. (Arcturus) and Solid Biosciences Inc. (Solid) by using the quoted market prices, which are Level 1 fair value measurements. The following tables set forth the fair value of the Company’s financial assets remeasured on a recurring basis based on the three-tier fair value hierarchy (in thousands): September 30, 2022 Level 1 Level 2 Level 3 Total Money market funds $ 357,285 $ — $ — $ 357,285 Certificate of deposits and time deposits — 29,100 — 29,100 Corporate bonds — 380,957 — 380,957 Commercial paper — 82,137 — 82,137 Asset-backed securities — — — - U.S. Government Treasury and agency securities 19,081 90,758 — 109,839 Debt securities in government-sponsored entities — 15,747 — 15,747 Investments in Arcturus and Solid common stock 11,061 — — 11,061 Other — 4,063 — 4,063 Total $ 387,427 $ 602,762 $ — $ 990,189 December 31, 2021 Level 1 Level 2 Level 3 Total Money market funds $ 266,765 $ — $ — $ 266,765 Certificate of deposits and time deposits — 16,000 — 16,000 Corporate bonds — 349,691 — 349,691 Commercial paper — 187,624 — 187,624 Asset-backed securities — 41,245 — 41,245 U.S. Government Treasury and agency securities — 87,435 — 87,435 Debt securities in government-sponsored entities — 19,549 — 19,549 Investments in Arcturus and Solid common stock 32,200 — — 32,200 Other — 942 — 942 Total $ 298,965 $ 702,486 $ — $ 1,001,451

Balance Sheet Components

Balance Sheet Components	9 Months Ended
	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Balance Sheet Components	4. Balance Sheet Components Cash Equivalents and Investments The fair values of cash equivalents and investments classified as available-for-sale securities consisted of the following (in thousands): September 30, 2022 Gross Unrealized Amortized Gains Losses Estimated Money market funds $ 357,285 $ — $ — $ 357,285 Certificates of deposit and time deposits 29,100 — — 29,100 Corporate bonds 388,158 — ( 7,201 ) 380,957 Commercial paper 82,137 — — 82,137 Asset-backed securities — — — — U.S. Government Treasury and agency securities 111,248 8 ( 1,417 ) 109,839 Debt securities in government-sponsored entities 16,027 — ( 280 ) 15,747 Total $ 983,955 $ 8 $ ( 8,898 ) $ 975,065 December 31, 2021 Gross Unrealized Amortized Gains Losses Estimated Money market funds $ 266,765 $ — $ — $ 266,765 Certificates of deposit and time deposits 16,000 — — 16,000 Corporate bonds 350,667 3 ( 979 ) 349,691 Commercial paper 187,624 — — 187,624 Asset-backed securities 41,282 1 ( 38 ) 41,245 U.S. Government Treasury and agency securities 87,642 1 ( 208 ) 87,435 Debt securities in government-sponsored entities 19,612 — ( 63 ) 19,549 Total $ 969,592 $ 5 $ ( 1,288 ) $ 968,309 At September 30, 2022 , the remaining contractual maturities of available-for-sale securities were less than three years . There have been no significant realized gains or losses on available-for-sale securities for the three and nine months ended September 30, 2022 and 2021. The unrealized losses on the Company’s investments in marketable debt securities were caused by interest rate increases. At September 30, 2022, thirty corporate bond securities with an aggregate fair value of $ 77.7 million and an aggregate unrealized loss of $ 1.7 million were in a loss position for more than twelve months. The contractual terms of these investments do not permit the issuers to settle the securities at a price less than the par value. Accordingly, it is expected that the securities will not be settled at a price less than the amortized cost basis of these investments. The Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost basis. Inventory Inventory consists of the following (in thousands): September 30, December 31, 2022 2021 Work-in-process $ 15,777 $ 10,504 Finished goods 6,072 5,727 Total inventory $ 21,849 $ 16,231 Accrued Liabilities Accrued liabilities consist of the following (in thousands): September 30, December 31, 2022 2021 Research, clinical study, and manufacturing expenses $ 61,921 $ 40,880 Payroll and related expenses 67,197 62,591 Other 59,933 42,084 Total accrued liabilities $ 189,051 $ 145,555

Revenue

Revenue	9 Months Ended
	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Revenue	5. Revenue The following table disaggregates total revenues from customers (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2022 2021 2022 2021 Collaboration and license revenue: Crysvita collaboration revenue in profit- $ 51,348 $ 42,971 $ 148,121 $ 120,987 Crysvita royalty revenue in European — 16 — 244 Daiichi Sankyo 1,479 12,061 6,207 76,767 Total collaboration and license revenue 52,827 55,048 154,328 197,998 Product sales: Crysvita 13,184 7,378 34,980 16,150 Mepsevii 6,045 3,918 15,839 12,924 Dojolvi 13,274 10,654 39,200 27,735 Total product sales 32,503 21,950 90,019 56,809 Crysvita non-cash collaboration royalty 5,373 4,649 15,634 13,210 Total revenues $ 90,703 $ 81,647 $ 259,981 $ 268,017 The following table disaggregates total revenues based on geographic location (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2022 2021 2022 2021 U.S. and Canada $ 67,012 $ 66,911 $ 196,257 $ 230,220 Europe 8,411 7,244 26,114 19,581 Latin America 14,119 7,492 36,449 18,216 Japan 1,161 — 1,161 — Total revenues $ 90,703 $ 81,647 $ 259,981 $ 268,017 The following table presents changes in the contract liabilities (in thousands): Nine Months Ended September 30, 2022 2021 Balance of contract liabilities at beginning of period $ ( 9,076 ) $ ( 66,568 ) Additions ( 89 ) ( 2,390 ) Deductions 6,207 76,767 Balance of contract assets (liabilities) at end of period $ ( 2,958 ) $ 7,809 See Note 7 for additional details on contract liabilities activities. The Company’s largest accounts receivable balance accounted for 49 % and 71 % of the total accounts receivable balance as of September 30, 2022 and December 31, 2021, respectively, and was due from a collaboration partner. The accounts receivable balance from a different customer accounted for 16 % and nil of the total accounts receivable balance as of September 30, 2022 and December 31, 2021, respectively.

GeneTx Acquisition

GeneTx Acquisition	9 Months Ended
	Sep. 30, 2022
Business Combinations [Abstract]
Acquisition	6. GeneTx Acquisition In August 2019, the Company entered into a Program Agreement and a Unitholder Option Agreement with GeneTx to collaborate on the development of GeneTx’s GTX-102, an ASO for the treatment of Angelman syndrome. Pursuant to the terms of the Unitholder Option Agreement, the Company made an upfront payment of $ 20.0 million for an exclusive option to acquire GeneTx, which was exercisable any time prior to 30 days following FDA acceptance of the IND for GTX-102. Pursuant to the agreement, upon acceptance of the IND, which occurred in January 2020, the Company elected to extend the option period by paying an option extension payment of $ 25.0 million (option extension premium) during the quarter ended March 31, 2020, which was recorded as an in-process research and development expense. In April 2022, the parties entered into an amendment to the Unitholder Option Agreement (the “Amendment”) which provided the Company with an additional, earlier option to acquire GeneTx for an option exercise price of $ 75.0 million based on the earlier of receipt of interim data in the Phase 1/2 study or a specified date (such option, the “Interim Option”). During the exclusive option period, GeneTx was responsible for conducting the program based on the development plan agreed upon between the parties and, subject to the terms in the Program Agreement, had the decision-making authority on all matters in connection with the research, development, manufacturing and regulatory activities with respect to the Program. In July 2022, the Company exercised the Interim Option to acquire GeneTx and entered into a Unit Purchase Agreement (the Purchase Agreement) pursuant to which the Company purchased all the outstanding units of GeneTx. In accordance with the terms of the Purchase Agreement, the Company paid the option exercise price of $ 75.0 million, an additional $ 15.6 million to acquire the outstanding cash of GeneTx, and customary adjustments for working capital and transaction expenses of $ 0.6 million, for a total purchase consideration of $ 91.2 million. Additionally, the Company may make payments of up to $ 190.0 million upon the achievement of certain milestones, including up to $ 30.0 million in milestone payments upon achievement of the earlier of initiation of a Phase 3 clinical study or product approvals in Canada and the U.K., up to $ 85.0 million in additional regulatory approval milestones for the achievement of U.S. and EU product approvals, and up to $ 75.0 million in commercial milestone payments based on annual worldwide net product sales. In addition, the Company will also pay tiered mid- to high single-digit percentage royalties based on licensed product annual net sales. If the Company receives and resells an FDA priority review voucher (PRV) in connection with a new drug application approval, GeneTx is entitled to receive a portion of proceeds from the sale or a cash payment from the Company if the Company choses to retain the PRV. The transaction was accounted as an asset acquisition, as substantially all of the fair value of the gross assets acquired was concentrated in a single identifiable in-process research and development intangible asset. Prior to achievement of certain development and regulatory milestones, the acquired in-process research and development intangible asset has not yet reached technological feasibility and has no alternative future use. Accordingly, the Company recorded $ 75.2 million, net of cash and working capital acquired, as in-process research and development expense during the three months ended September 30, 2022.

License and Research Agreements

License and Research Agreements	9 Months Ended
	Sep. 30, 2022
Research Grant Agreement [Abstract]
License and Research Agreements	7. License and Research Agreements Kyowa Kirin Collaboration and License Agreement In August 2013, the Company entered into a collaboration and license agreement with Kyowa Kirin Co., Ltd. (KKC formerly Kyowa Hakko Kirin Co., Ltd. or KHK). Under the terms of this collaboration and license agreement, as amended, the Company and KKC collaborate on the development and commercialization of Crysvita in the field of orphan diseases in the U.S. and Canada, (the profit-share territory), and in the European Union, United Kingdom, and Switzerland, (the European territory), and the Company has the right to develop and commercialize such products in the field of orphan diseases in Mexico and Central and South America, or Latin America. Development activities In the field of orphan diseases, and except for ongoing studies being conducted by KKC, the Company is the lead party for development activities in the profit-share territory and in the European territory until the applicable transition date. The Company shares the costs for development activities in the profit-share territory and the European territory conducted pursuant to the development plan before the applicable transition date equally with KKC. In April 2023, which is the transition date for the profit-share territory, KKC will become the lead party and be responsible for the costs of the development activities. However, the Company will continue to share the costs of the studies commenced prior to the applicable transition date equally with KKC. The collaboration and license agreements are within the scope of ASC 808, which provides guidance on the presentation and disclosure of collaborative arrangements. Collaboration revenue related to sales in profit-share territory The Company and KKC share commercial responsibilities and profits in the profit-share territory until April 2023. Under the collaboration agreement, KKC manufactures and supplies Crysvita for commercial use in the profit-share territory and charges the Company a transfer price of 35 % of net sales through December 31, 2022, and 30 % thereafter. The remaining profit or loss after supply costs from commercializing products in the profit-share territory are shared between the Company and KKC on a 50 / 50 basis until April 2023. In April 2023, commercialization responsibilities for Crysvita in the profit-share territory will transition to KKC and KKC will be responsible for the commercialization of Crysvita in the territory at and after April 2023. Thereafter, the Company will be entitled to receive a tiered double-digit revenue share from the mid- 20 % range up to a maximum rate of 30 %. In September 2022, the Company entered into an amendment to the collaboration agreement which clarified the scope of increased participation by KKC in support of the Company’s commercial activities prior to April 2023 and granted the Company the right to continue to support KKC in commercial field activities in the U.S. through April 2024, subject to the limitations and conditions set forth in the amendment. As a result, KKC will continue to support the Company’s commercial field and marketing efforts through a cost share arrangement through April 2024, subject to the limits and conditions set forth in the amendment. After April 2024, the Company’s rights to promote Crysvita in the U.S. will be limited to medical geneticists and the Company will solely bear the cost of its own expenses related to the promotion of Crysvita in the profit-share territory. As KKC is the principal in the sale transaction with the customer, the Company recognizes a pro-rata share of collaboration revenue, net of transfer pricing, in the period the sale occurs. The Company concluded that its portion of KKC’s sales in the profit-share territory is analogous to a royalty and therefore recorded its share as collaboration revenue, similar to a royalty. In July 2022, the Company sold to OMERS its right to receive 30 % of the future royalty payments due to the Company based on net sales of Crysvita in the U.S. and Canada, subject to a cap, beginning in April 2023, as further described in Note 8. Royalty revenue related to sales in European territory KKC has the commercial responsibility for Crysvita in the European territory. In December 2019, the Company sold its right to receive royalty payments based on sales in the European territory to Royalty Pharma, effective January 1, 2020, as further described in Note 8. Prior to the Company’s sale of the royalty, the Company received a royalty of up to 10 % on net sales in the European territory, which was recognized as the underlying sales occur. Beginning in 2020, the Company recorded the royalty revenue as non-cash royalty revenues. The Company’s share of collaboration and royalty revenue related to Crysvita was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Company’s share of revenue in profit- $ 51,348 $ 42,971 $ 148,121 $ 120,987 Royalty revenue in European territory — 16 — 244 Non-cash royalty revenue in European 5,373 4,649 15,634 13,210 Total $ 56,721 $ 47,636 $ 163,755 $ 134,441 Product revenue related to sales in other territories The Company is responsible for commercializing Crysvita in Latin America and Turkey. The Company is considered the principal in these territories as the Company controls the product before it is transferred to the customer. Accordingly, the Company records revenue on a gross basis related to the sale of Crysvita once the product is delivered and the risk and title of the product is transferred to the distributor. The Company recorded product sales of $ 13.2 million and $ 35.0 million for the three and nine months ended September 30, 2022, respectively, and $ 7.4 million and $ 16.2 million for the three and nine months ended September 30, 2021, respectively, net of estimated product returns and other deductions. KKC has the option to assume responsibility for commercialization efforts in Turkey from the Company, after a certain minimum period. Under the collaboration agreement, KKC manufactures and supplies Crysvita, which is purchased by the Company for sales in its territories and is based on 35 % of the net sales through December 31, 2022 and 30 % thereafter. The Company also pays to KKC a low single-digit royalty on net sales in Latin America. Cost sharing payments Under the collaboration agreement, KKC and the Company share certain development and commercialization costs. As a result, the Company was reimbursed for these costs and operating expenses were reduced as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Research and development $ 3,830 $ 5,161 $ 12,770 $ 16,517 Selling, general and administrative 8,365 8,005 26,510 23,076 Total $ 12,195 $ 13,166 $ 39,280 $ 39,593 Collaboration receivable and payable The Company had accounts receivable from KKC in the amount of $ 15.2 million and $ 20.2 million from profit-share revenue and royalties and other receivables recorded in prepaid expenses and other current assets of $ 3.2 million and $ 16.0 million and accrued liabilities of $ 5.1 million and $ 2.3 million from commercial and development activity reimbursements, as of September 30, 2022 and December 31, 2021, respectively. Daiichi Sankyo In March 2020, the Company executed a License and Technology Access Agreement (the License Agreement) with Daiichi Sankyo Co., Ltd. (Daiichi Sankyo). Pursuant to the License Agreement, the Company granted Daiichi Sankyo a non-exclusive license to intellectual property, including know-how and patent applications, with respect to its Pinnacle PCL TM producer cell line platform (Pinnacle PCL Platform), and HEK293 transient transfection manufacturing technology platforms for AAV-based gene therapy products. Under the terms of the License Agreement, Daiichi Sankyo made an upfront payment of $ 125.0 million and an additional $ 25.0 million upon completion of the technology transfer of the Pinnacle PCL Platform and HEK293 platform. Daiichi Sankyo reimbursed the Company for all costs associated with the transfer of the manufacturing technology and will pay single-digit royalties on net sales of products manufactured in either system. The Company also entered into a Stock Purchase Agreement (SPA) with Daiichi Sankyo, pursuant to which Daiichi Sankyo purchased 1,243,913 shares of the Company’s common stock in exchange for $ 75.0 million in cash during the first quarter of 2020. The fair market value of the common stock issued to Daiichi Sankyo was $ 55.3 million based on the stock price of $ 44.43 per share on the date of issuance, resulting in a $ 19.7 million premium on the SPA. Daiichi Sankyo is also subject to a three-year standstill and restrictions on sale of the shares (subject to customary exceptions or release). In June 2020, the Company executed a subsequent license agreement (the Sublicense Agreement) with Daiichi Sankyo for transfer of certain technology in consideration for an upfront payment of $ 8.0 million and annual maintenance fees, milestone payments, and royalties on any net sales of products incorporating the licensed intellectual property. The License Agreement, the Sublicense Agreement, and the SPA are being accounted for as one arrangement because they were entered into at or near the same time and negotiated in contemplation of one another. The Company evaluated the License Agreement and the Sublicense Agreement under ASC 606 and determined that the performance obligations under the agreements are (i) intellectual property with respect to its Pinnacle PCL Platform and HEK293 transient transfection manufacturing technology platform together with the initial technical assistance and technology transfer services, which was completed in the first quarter of 2022, and (ii) the transfer of any know-how and improvements after the completion of the initial technology transfer through the end of the three year technology transfer period ending March 2023. As of September 30, 2022 , the Company has determined that the total transaction price of the License Agreement was $ 183.4 million, which was comprised of the $ 19.7 million premium from the SPA, the $ 125.0 million upfront payment, the $ 25.0 million in unconstrained milestone payments, $ 8.0 million from the Sublicense Agreement, and the $ 5.7 million estimated reimbursement amount for delivering the license and technology services. Total revenue recognized under the license agreement through September 30, 2022 was $ 180.4 million. The Company allocated the total transaction price to the two performance obligations on a relative stand-alone selling price basis. Revenue allocated to the intellectual property and the technology transfer services was recognized over an initial period which was completed during the first quarter of 2022, measuring the progress toward complete satisfaction of the individual performance obligation using an input measure. Revenue for know-how and improvements after the completion of technology transfer is being recognized on a straight-line basis over the remaining technology transfer period, which ends in March 2023, as it is expected that Daiichi Sankyo will receive and consume the benefits consistently throughout the period. Royalties from commercial sales will be accounted for as revenue upon achievement of such sales, assuming all other revenue recognition criteria are met. The Company recognized $ 1.5 million and $ 6.2 million for the three and nine months ended September 30, 2022, respectively, and $ 12.1 million and $ 76.8 million for the three and nine months ended September 30, 2021 , respectively, in revenue related to this arrangement. Accordingly, the Company recorded $ 3.0 million and $ 9.1 million of contract liabilities, net, as of September 30, 2022 and December 31, 2021, respectively. The Company recorded an accounts receivable related to the above agreements of nil and $ 0.1 million as of September 30, 2022 and December 31, 2021, respectively. Mereo In December 2020, the Company entered into a License and Collaboration Agreement with Mereo to collaborate on the development of setrusumab. Under the terms of the agreement, the Company will lead future global development of setrusumab in both pediatric and adult patients with OI. The Company was granted an exclusive license to develop and commercialize setrusumab in the U.S., Turkey, and the rest of the world, excluding the European Economic Area, United Kingdom, and Switzerland (the Mereo territory), where Mereo retains commercial rights. Each party will be responsible for post-marketing commitments and commercial supply in their respective territories. Upon closing of the transaction in January 2021, the Company made a payment of $ 50.0 million to Mereo and will be required to make payments of up to $ 254.0 million upon the achievement of certain clinical, regulatory, and commercial milestones. The Company will pay for all global development costs as well as tiered double-digit percentage royalties to Mereo on net sales in the U.S., Turkey, and the rest of the world (excluding the Mereo Territory), and Mereo will pay the Company a fixed double-digit percentage royalty on net sales in the Mereo Territory. Although Mereo is a variable interest entity, the Company is not the primary beneficiary as it does not have the power to direct the activities that would most significantly impact the economic performance of Mereo. Prior to the achievement of certain development milestones, all consideration paid to Mereo represents rights to potential future benefits associated with Mereo’s in-process research and development activities, which have not reached technological feasibility and have no alternative future use. Accordingly, for the three months ended March 31, 2021, the Company recorded the upfront payment of $ 50.0 million as in-process research and development expense. Regeneron In January 2022, the Company announced a collaboration with Regeneron to commercialize Evkeeza for HoFH outside of the U.S. Evkeeza is approved in the U.S., where it is marketed by Regeneron, and in the EEA as a first-in-class therapy for use together with diet and other low-density lipoprotein-cholesterol- lowering therapies to treat adults and adolescents aged 12 years and older with HoFH. Pursuant to the terms of the agreement, the Company received the rights to develop, commercialize and distribute the product for HoFH in countries outside of the U.S. The Company may be obligated to pay up to $ 63.0 million in future milestone payments, contingent upon the achievement of certain regulatory and sales milestones. The Company will share in certain costs for global trials led by Regeneron and also has the right to opt into other potential indications, including an exclusive right to negotiate a separate agreement with Regeneron to collaborate on the development and commercialization outside of the U.S. of Regeneron’s investigational antibody for the treatment of fibrodysplasia ossificans progressiva (FOP). The Company’s option to negotiate an agreement for the treatment of FOP expired in July 2022. The collaboration agreement is within the scope of ASC 808 which provides guidance on the presentation and disclosure of collaborative arrangements. As the Company would be the principal in future sale transactions with the customer, the Company will recognize product sales and cost of sales in the period the related sale occurs and the related revenue recognition criteria are met. Under the collaboration agreement, Regeneron will supply the product and will charge the Company a transfer price from the low 20 % range up to 40 % on net sales, which will be recognized as cost of sales in the Company’s Statement of Operations. Upon closing of the transaction in January 2022, the Company paid Regeneron a $ 30.0 million upfront payment. As the upfront payment was related to the Company’s usage of intellectual property related to Evkeeza for HoFH, the upfront payment was recorded on the Consolidated Balance Sheet as an intangible asset, which is being amortized over its useful life of 10.5 years. The Company recorded costs of goods sold of $ 0.7 million and $ 2.1 million for the three and nine months ended September 30, 2022 , respectively, related to the amortization of the intangible asset. Further, the Company reimbursed Regeneron for certain development costs of $ 2.5 million and $ 4.3 million for the three and nine months ended September 30, 2022 , respectively. No revenue was recorded for Evkeeza for the three and nine months ended September 30, 2022. Abeona In May 2022, the Company announced an exclusive License Agreement for the AAV gene therapy for UX111 with Abeona for the treatment of MPS IIIA. Under the terms of the agreement, the Company assumed responsibility for the UX111 program and in return, Abeona is eligible to receive tiered royalties of up to 10 % on net sales and commercial milestone payments of up to $ 30.0 million following regulatory approval of the product. Additionally, the Company entered into an Assignment and Assumption Agreement with Abeona to transfer and assign to the Company the exclusive license agreement between Nationwide Children’s Hospital (NCH) and Abeona for certain rights related to UX111. Under this agreement, NCH is eligible to receive from the Company up to $ 1.0 million in development and regulatory milestones as well as royalties in the low single-digits of net sales. The Company is obligated to pay Abeona certain prior development costs and other transition costs related to UX111. Prior to product regulatory approval, all consideration paid to Abeona represents rights to potential future benefits associated with Abeona’s in-process research and development activities, which have not reached technological feasibility and have no alternative future use. Accordingly, the value of the acquired intellectual property rights and clinical inventory as well as prior development costs and transition costs amounting to $ 0.8 million and $ 2.9 million were recorded as research and development expense for the three and nine months ended September 30, 2022, respectively. Bayer In October 2022, the Collaboration and License Agreement for DTX201 with Bayer was terminated and all licensed rights to DTX201 have reverted back to the Company. The Company also obtained rights to all necessary data and information to further develop DTX201 or another hemophilia A program through a royalty free, worldwide, sublicensable, perpetual license. Other Arrangements The Company has also entered into several collaborations and/or licensing arrangements in prior periods. Except as disclosed above, there have not been material changes in these arrangements as disclosed in Note 7 to the Consolidated Financial Statements in the Annual Report. Under the financial terms of these arrangements, the Company may be required to make payments upon achievement of developmental, regulatory, and commercial milestones, which could be significant. Future milestone payments, if any, will be reflected in the Condensed Consolidated Statements of Operations upon the occurrence of the contingent event. In addition, the Company may be required to pay royalties on future sales if products related to these arrangements are commercialized. The payment of these amounts, however, is contingent upon the occurrence of various future events, which have a high degree of uncertainty of occurrence. As described in the Annual Report, in connection with the Company’s collaborations with Solid and Arcturus, the Company holds certain equity interests in each entity. The changes in the fair value of the Company’s equity investments in the common stock of Solid and Arcturus were as follows (in thousands): Common stock As of December 31, 2020 $ 154,756 Change in fair value ( 42,713 ) Sale of shares ( 79,843 ) December 31, 2021 32,200 Change in fair value ( 21,139 ) September 30, 2022 $ 11,061

Liability Related to the Sale o

Liability Related to the Sale of Future Royalties	9 Months Ended
	Sep. 30, 2022
Deferred Revenue Disclosure [Abstract]
Liabilities Related to the Sale of Future Royalties	8. Liabilities Related to the Sale of Future Royalties In December 2019, the Company entered into a Royalty Purchase Agreement with RPI. Pursuant to the agreement, RPI paid $ 320.0 million to the Company in consideration for the right to receive royalty payments effective January 1, 2020, arising from the net sales of Crysvita in the European Union, the United Kingdom, and Switzerland under the terms of the Company’s Collaboration and License Agreement with KKC dated August 29, 2013, as amended (KKC Collaboration Agreement). The agreement with RPI will automatically terminate, and the payment of royalties to RPI will cease, in the event aggregate royalty payments received by RPI are equal to or greater than $ 608.0 million prior to December 31, 2030, or in the event aggregate royalty payments received by RPI are less than $ 608.0 million prior to December 31, 2030, when aggregate royalty payments received by RPI are equal to $ 800.0 million . In July 2022, the Company entered into a Royalty Purchase Agreement with OMERS. Pursuant to the agreement, OMERS paid $ 500.0 million to the Company in consideration for the right to receive 30 % of the future royalty payments due to the Company from KKC based on net sales of Crysvita in the U.S. and Canada under the terms of the KKC Collaboration Agreement. The calculation of royalty payments to OMERS will be based on net sales of Crysvita beginning in April 2023 and will expire upon the earlier of the date on which aggregate payments received by OMERS equals $ 725.0 million or the date the final royalty payment is made to the Company under the KKC Collaboration Agreement. Proceeds from these transactions were recorded as liabilities (liabilities related to sale of future royalties on the Consolidated Balance Sheets). The Company amortizes $ 320.0 million and $ 500.0 million, net of transaction costs of $ 5.8 million and $ 9.1 million for RPI and OMERS, respectively, using the effective interest method over the estimated life of the applicable arrangement. In order to determine the amortization of the liabilities, the Company is required to estimate the total amount of future royalty payments to be received by the Company and paid to RPI and OMERS, subject to the capped amount, over the life of the arrangements. The excess of future estimated royalty payments (subject to the capped amount), over the $ 314.2 million and $ 491.0 million, respectively, of net proceeds, is recorded as non-cash interest expense over the life of the arrangements. Consequently, the Company estimates an imputed interest on the unamortized portion of the liabilities and records interest expense relating to the transactions. The Company records the royalty revenue arising from the net sales of Crysvita in the applicable territories as non-cash royalty revenue in the Consolidated Statements of Operations over the term of the arrangements. The Company periodically assesses the expected royalty payments using a combination of historical results, internal projections and forecasts from external sources. To the extent such payments are greater or less than the Company’s initial estimates or the timing of such payments is materially different than its original estimates, the Company will prospectively adjust the amortization of the liabilities and the effective interest rate. The Company’s effective annual interest rate was approximately 9.6 % and 8.3 %, for RPI and OMERS, respectively, as of September 30, 2022. There are a number of factors that could materially affect the amount and timing of royalty payments from KKC in the applicable territories, most of which are not within the Company’s control. Such factors include, but are not limited to, the success of KKC’s sales and promotion of Crysvita, changing standards of care, delays or disruptions related to the COVID-19 pandemic, macroeconomic and inflationary pressures, the introduction of competing products, pricing for reimbursement in various territories, manufacturing or other delays, intellectual property matters, adverse events that result in governmental health authority imposed restrictions on the use of Crysvita, significant changes in foreign exchange rates as the royalty payments are made in U.S. dollars (USD) while significant portions of the underlying sales of Crysvita are made in currencies other than USD, and other events or circumstances that could result in reduced royalty payments from sales of Crysvita, all of which would result in a reduction of non-cash royalty revenue and the non-cash interest expense over the life of the arrangement. Conversely, if sales of Crysvita in the relevant territories are more than expected, the non-cash royalty revenue and the non-cash interest expense recorded by the Company would be greater over the term of the arrangements. The following table shows the activity within the liabilities account (in thousands): RPI OMERS Liabilities related to the sale of future royalties December 31, 2020 $ 335,665 $ — $ 335,665 Non-cash collaboration royalty revenue ( 17,951 ) — ( 17,951 ) Non-cash interest expense 34,072 — 34,072 December 31, 2021 351,786 — 351,786 Net proceeds from sale of future — 490,950 490,950 Non-cash collaboration royalty revenue ( 15,634 ) — ( 15,634 ) Non-cash interest expense 26,247 8,714 34,961 September 30, 2022 $ 362,399 $ 499,664 $ 862,063

Stock-Based Awards

Stock-Based Awards	9 Months Ended
	Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]
Stock-Based Awards	9. Stock-Based Awards The 2014 Incentive Plan (the 2014 Plan) provides for automatic annual increases in shares available for grant, beginning on January 1, 2015 through January 1, 2024 . As of September 30, 2022 , there were 2,034,566 shares reserved under the 2014 Plan for the future issuance of equity awards, 4,640,287 shares reserved under the 2014 Employee Stock Purchase Plan, and 322,697 shares reserved for the Employment Inducement Plan. The table below sets forth the stock-based compensation expense for the periods presented (in thousands): Three Months Ended Nine Months Ended 2022 2021 2022 2021 Cost of sales $ 225 $ 160 $ 730 $ 762 Research and development 20,251 15,366 57,588 43,949 Selling, general and administrative 15,285 11,464 42,695 33,719 Total stock-based compensation expense $ 35,761 $ 26,990 $ 101,013 $ 78,430

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2022
Earnings Per Share [Abstract]
Net Loss Per Share	10. Net Loss Per Share Basic net loss per share has been computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share is calculated by dividing net loss by the weighted-average number of shares of common stock and potential dilutive securities outstanding during the period. The following weighted-average outstanding common stock equivalents were excluded from the computation of diluted net loss per share for the periods presented because including them would have been antidilutive: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Options to purchase common stock, 11,969,532 8,287,010 11,114,822 8,287,394 Employee stock purchase plan 44,649 30,196 15,047 16,923 12,014,181 8,317,206 11,129,869 8,304,317

Equity Transactions

Equity Transactions	9 Months Ended
	Sep. 30, 2022
Equity [Abstract]
Equity Transactions	11. Equity Transactions In May 2021, the Company entered into an Open Market Sale Agreement with Jefferies LLC, (Jefferies), pursuant to which the Company may offer and sell shares of the Company’s common stock having an aggregate offering proceeds up to $ 350.0 million, from time to time, in at-the-market (ATM) offerings through Jefferies. As of September 30, 2022 , the Company has sold 1,050,372 shares under the arrangement resulting in net proceeds of approximately $ 78.9 million. No shares were sold under the arrangement for the three and nine months ended September 30, 2022 .

Related Party Transaction

Related Party Transaction	9 Months Ended
	Sep. 30, 2022
Related Party Transactions [Abstract]
Related Party Transaction	12. Related Party Transaction In July 2022, the Company entered into an agreement with a non-profit foundation in which two of the Company’s board members, including the Company’s Chief Executive Officer, are also board members of the foundation, whereby a $ 1.0 million contribution will be paid out to the foundation over a four-year period, beginning in third quarter of 2022, to support rare disease education and awareness. As a result, the Company recorded $ 0.3 million as research and development expense for this agreement for the three and nine months ended September 30, 2022 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 30, 2022
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Loss	13. Accumulated Other Comprehensive Loss Total accumulated other comprehensive loss consisted of the following (in thousands): September 30, December 31, 2022 2021 Foreign currency translation adjustments $ ( 1,332 ) $ ( 121 ) Unrealized loss on available-for-sale securities ( 8,890 ) ( 1,283 ) Total accumulated other comprehensive loss $ ( 10,222 ) $ ( 1,404 )

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries and have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information and in accordance with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. The unaudited interim Condensed Consolidated Financial Statements have been prepared on the same basis as the annual financial statements. In the opinion of management, the accompanying unaudited Condensed Consolidated Financial Statements reflect all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation. These financial statements should be read in conjunction with the audited financial statements and notes thereto for the preceding fiscal year contained in the Company’s Annual Report on Form 10-K filed on February 15, 2022 (Annual Report) with the U.S. Securities and Exchange Commission (the SEC). The results of operations for the three and nine months ended September 30, 2022 are not necessarily indicative of the results to be expected for the year ending December 31, 2022. The Condensed Consolidated Balance Sheet as of December 31, 2021 has been derived from audited financial statements at that date, but does not include all of the information required by GAAP for complete financial statements.
Use of Estimates	Use of Estimates The accompanying Condensed Consolidated Financial Statements have been prepared in accordance with GAAP. The preparation of the Condensed Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities and the reported amounts of expenses in the Condensed Consolidated Financial Statements and the accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to clinical trial accruals, fair value of assets and liabilities, income taxes, stock-based compensation, revenue recognition, and liabilities related to the sale of future royalties. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Cash, Cash Equivalents, and Restricted Cash	Cash, Cash Equivalents and Restricted Cash Restricted cash primarily consists of money market accounts used as collateral for the Company’s obligations under its facility leases. The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the Condensed Consolidated Balance Sheets that sum to the total of the same such amounts shown in the Condensed Consolidated Statement of Cash Flows (in thousands): September 30, 2022 2021 Cash and cash equivalents $ 391,651 $ 197,538 Restricted cash included in prepaid expenses and 517 10,000 Restricted cash included in other assets 4,140 2,001 Total cash, cash equivalents, and restricted cash $ 396,308 $ 209,539
Credit Losses	Credit Losses The Company is exposed to credit losses primarily through receivables from customers and collaborators and through its available-for-sale debt securities. For trade receivables and other instruments, the Company uses a forward-looking expected loss model that generally results in the earlier recognition of allowances for losses. For available-for-sale debt securities with unrealized losses, the losses are recognized as allowances rather than as reductions in the amortized cost of the securities. The Company’s expected loss allowance methodology for the receivables is developed using historical collection experience, current and future economic market conditions, a review of the current aging status and financial condition of the entities. Specific allowance amounts are established to record the appropriate allowance for customers that have a higher probability of default. Balances are written off when determined to be uncollectible. The Company’s expected loss allowance methodology for the debt securities is developed by reviewing the extent of the unrealized loss, the size, term, geographical location, and industry of the issuer, the issuers’ credit ratings and any changes in those ratings, as well as reviewing current and future economic market conditions and the issuers’ current status and financial condition. There were no material credit losses recorded for receivables and available-for-sale debt securities for the three and nine months ended September 30, 2022 and 2021.
Revenue Recognition	Revenue Recognition Collaboration and license revenue The Company has certain license and collaboration agreements that are within the scope of Accounting Standards Codification (ASC) 808, Collaborative Agreements , which provides guidance on the presentation and disclosure of collaborative arrangements. Generally, the classification of the transactions under the collaborative arrangements is determined based on the nature of contractual terms of the arrangement, along with the nature of the operations of the participants. The Company records its share of collaboration revenue, net of transfer pricing related to net sales in the period in which such sales occur, if the Company is considered as an agent in the arrangement. The Company is considered an agent when the collaboration partner controls the product before transfer to the customers and has the ability to direct the use of and obtain substantially all of the remaining benefits from the product. Funding received related to research and development services and commercialization costs is generally classified as a reduction of research and development expenses and selling, general and administrative expenses, respectively, in the Condensed Consolidated Statement of Operations, because the provision of such services for collaborative partners are not considered to be part of the Company’s ongoing major or central operations. In order to record collaboration revenue, the Company utilizes certain information from its collaboration partners, including revenue from the sale of the product, associated reserves on revenue, and costs incurred for development and sales activities. For the periods covered in the financial statements presented, there have been no material changes to prior period estimates of revenues and expenses. The Company sold the right to receive certain royalty payments from net sales of Crysvita in certain territories to RPI Finance Trust (RPI), an affiliate of Royalty Pharma, and to OCM LS23 Holdings LP, an investment vehicle for Ontario Municipal Employees Retirement System (OMERS) as further described in Note 8. The Company records the royalty revenue from the net sales of Crysvita in the applicable territories on a prospective basis as non-cash royalty revenue in the Condensed Consolidated Statements of Operations over the term of the applicable arrangement. The terms of the Company’s collaboration and license agreements may contain multiple performance obligations, which may include licenses and research and development activities. The Company evaluates these agreements under ASC 606, Revenue from Contracts with Customers (ASC 606), to determine the distinct performance obligations. The Company analogizes to ASC 606 for the accounting for distinct performance obligations for which there is a customer relationship. Prior to recognizing revenue, the Company makes estimates of the transaction price, including variable consideration that is subject to a constraint. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. Total consideration may include nonrefundable upfront license fees, payments for research and development activities, reimbursement of certain third-party costs, payments based upon the achievement of specified milestones, and royalty payments based on product sales derived from the collaboration. If there are multiple distinct performance obligations, the Company allocates the transaction price to each distinct performance obligation based on its relative standalone selling price. The standalone selling price is generally determined based on the prices charged to customers or using expected cost-plus margin. The Company estimates the efforts needed to complete the performance obligations and recognizes revenue by measuring the progress towards complete satisfaction of the performance obligations using input measures. Product sales The Company sells its approved products through a limited number of distributors. Under ASC 606, revenue from product sales is recognized at the point in time when the delivery is made and when title and risk of loss transfers to these distributors. The Company also recognizes revenue from sales of certain products on a “named patient” basis, which are allowed in certain countries prior to the commercial approval of the product. Prior to recognizing revenue, the Company makes estimates of the transaction price, including any variable consideration that is subject to a constraint. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. Product sales are recorded net of estimated government-mandated rebates and chargebacks, estimated product returns, and other deductions. Provisions for returns and other adjustments are provided for in the period the related revenue is recorded, as estimated by management. These reserves are based on estimates of the amounts earned or to be claimed on the related sales and are reviewed periodically and adjusted as necessary. The Company’s estimates of government mandated rebates, chargebacks, estimated product returns, and other deductions depends on the identification of key customer contract terms and conditions, as well as estimates of sales volumes to different classes of payors. If actual results vary, the Company may need to adjust these estimates, which could have an effect on earnings in the period of the adjustment.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the Condensed Consolidated Balance Sheets that sum to the total of the same such amounts shown in the Condensed Consolidated Statement of Cash Flows (in thousands): September 30, 2022 2021 Cash and cash equivalents $ 391,651 $ 197,538 Restricted cash included in prepaid expenses and 517 10,000 Restricted cash included in other assets 4,140 2,001 Total cash, cash equivalents, and restricted cash $ 396,308 $ 209,539

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Summary of Financial Assets Measured on Recurring Basis	The following tables set forth the fair value of the Company’s financial assets remeasured on a recurring basis based on the three-tier fair value hierarchy (in thousands): September 30, 2022 Level 1 Level 2 Level 3 Total Money market funds $ 357,285 $ — $ — $ 357,285 Certificate of deposits and time deposits — 29,100 — 29,100 Corporate bonds — 380,957 — 380,957 Commercial paper — 82,137 — 82,137 Asset-backed securities — — — - U.S. Government Treasury and agency securities 19,081 90,758 — 109,839 Debt securities in government-sponsored entities — 15,747 — 15,747 Investments in Arcturus and Solid common stock 11,061 — — 11,061 Other — 4,063 — 4,063 Total $ 387,427 $ 602,762 $ — $ 990,189 December 31, 2021 Level 1 Level 2 Level 3 Total Money market funds $ 266,765 $ — $ — $ 266,765 Certificate of deposits and time deposits — 16,000 — 16,000 Corporate bonds — 349,691 — 349,691 Commercial paper — 187,624 — 187,624 Asset-backed securities — 41,245 — 41,245 U.S. Government Treasury and agency securities — 87,435 — 87,435 Debt securities in government-sponsored entities — 19,549 — 19,549 Investments in Arcturus and Solid common stock 32,200 — — 32,200 Other — 942 — 942 Total $ 298,965 $ 702,486 $ — $ 1,001,451

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Summary of Cash Equivalents and Investments Classified as Available For Sale Securities	The fair values of cash equivalents and investments classified as available-for-sale securities consisted of the following (in thousands): September 30, 2022 Gross Unrealized Amortized Gains Losses Estimated Money market funds $ 357,285 $ — $ — $ 357,285 Certificates of deposit and time deposits 29,100 — — 29,100 Corporate bonds 388,158 — ( 7,201 ) 380,957 Commercial paper 82,137 — — 82,137 Asset-backed securities — — — — U.S. Government Treasury and agency securities 111,248 8 ( 1,417 ) 109,839 Debt securities in government-sponsored entities 16,027 — ( 280 ) 15,747 Total $ 983,955 $ 8 $ ( 8,898 ) $ 975,065 December 31, 2021 Gross Unrealized Amortized Gains Losses Estimated Money market funds $ 266,765 $ — $ — $ 266,765 Certificates of deposit and time deposits 16,000 — — 16,000 Corporate bonds 350,667 3 ( 979 ) 349,691 Commercial paper 187,624 — — 187,624 Asset-backed securities 41,282 1 ( 38 ) 41,245 U.S. Government Treasury and agency securities 87,642 1 ( 208 ) 87,435 Debt securities in government-sponsored entities 19,612 — ( 63 ) 19,549 Total $ 969,592 $ 5 $ ( 1,288 ) $ 968,309
Summary of Inventory	Inventory consists of the following (in thousands): September 30, December 31, 2022 2021 Work-in-process $ 15,777 $ 10,504 Finished goods 6,072 5,727 Total inventory $ 21,849 $ 16,231
Accrued Liabilities	Accrued liabilities consist of the following (in thousands): September 30, December 31, 2022 2021 Research, clinical study, and manufacturing expenses $ 61,921 $ 40,880 Payroll and related expenses 67,197 62,591 Other 59,933 42,084 Total accrued liabilities $ 189,051 $ 145,555

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Summary of Disaggregation of Total Revenues	The following table disaggregates total revenues from customers (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2022 2021 2022 2021 Collaboration and license revenue: Crysvita collaboration revenue in profit- $ 51,348 $ 42,971 $ 148,121 $ 120,987 Crysvita royalty revenue in European — 16 — 244 Daiichi Sankyo 1,479 12,061 6,207 76,767 Total collaboration and license revenue 52,827 55,048 154,328 197,998 Product sales: Crysvita 13,184 7,378 34,980 16,150 Mepsevii 6,045 3,918 15,839 12,924 Dojolvi 13,274 10,654 39,200 27,735 Total product sales 32,503 21,950 90,019 56,809 Crysvita non-cash collaboration royalty 5,373 4,649 15,634 13,210 Total revenues $ 90,703 $ 81,647 $ 259,981 $ 268,017 The following table disaggregates total revenues based on geographic location (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2022 2021 2022 2021 U.S. and Canada $ 67,012 $ 66,911 $ 196,257 $ 230,220 Europe 8,411 7,244 26,114 19,581 Latin America 14,119 7,492 36,449 18,216 Japan 1,161 — 1,161 — Total revenues $ 90,703 $ 81,647 $ 259,981 $ 268,017
Summary of Changes in Contract Liabilities	The following table presents changes in the contract liabilities (in thousands): Nine Months Ended September 30, 2022 2021 Balance of contract liabilities at beginning of period $ ( 9,076 ) $ ( 66,568 ) Additions ( 89 ) ( 2,390 ) Deductions 6,207 76,767 Balance of contract assets (liabilities) at end of period $ ( 2,958 ) $ 7,809

License and Research Agreemen_2

License and Research Agreements (Tables)	9 Months Ended
	Sep. 30, 2022
Share of Collaboration and Royalty Revenue Related to Crysvita	The Company’s share of collaboration and royalty revenue related to Crysvita was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Company’s share of revenue in profit- $ 51,348 $ 42,971 $ 148,121 $ 120,987 Royalty revenue in European territory — 16 — 244 Non-cash royalty revenue in European 5,373 4,649 15,634 13,210 Total $ 56,721 $ 47,636 $ 163,755 $ 134,441
Schedule of Cost Sharing Payments	Under the collaboration agreement, KKC and the Company share certain development and commercialization costs. As a result, the Company was reimbursed for these costs and operating expenses were reduced as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Research and development $ 3,830 $ 5,161 $ 12,770 $ 16,517 Selling, general and administrative 8,365 8,005 26,510 23,076 Total $ 12,195 $ 13,166 $ 39,280 $ 39,593
Schedule of Changes in Fair Value of Equity Investment	The changes in the fair value of the Company’s equity investments in the common stock of Solid and Arcturus were as follows (in thousands): Common stock As of December 31, 2020 $ 154,756 Change in fair value ( 42,713 ) Sale of shares ( 79,843 ) December 31, 2021 32,200 Change in fair value ( 21,139 ) September 30, 2022 $ 11,061

Liability Related to the Sale_2

Liability Related to the Sale of Future Royalties (Tables)	9 Months Ended
	Sep. 30, 2022
Deferred Revenue Disclosure [Abstract]
Schedule of Activity Within Liabilities Related to Sale of Future Royalties	The following table shows the activity within the liabilities account (in thousands): RPI OMERS Liabilities related to the sale of future royalties December 31, 2020 $ 335,665 $ — $ 335,665 Non-cash collaboration royalty revenue ( 17,951 ) — ( 17,951 ) Non-cash interest expense 34,072 — 34,072 December 31, 2021 351,786 — 351,786 Net proceeds from sale of future — 490,950 490,950 Non-cash collaboration royalty revenue ( 15,634 ) — ( 15,634 ) Non-cash interest expense 26,247 8,714 34,961 September 30, 2022 $ 362,399 $ 499,664 $ 862,063

Stock-Based Awards (Tables)

Stock-Based Awards (Tables)	9 Months Ended
	Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]
Summary of Stock-Based Compensation Expense	The table below sets forth the stock-based compensation expense for the periods presented (in thousands): Three Months Ended Nine Months Ended 2022 2021 2022 2021 Cost of sales $ 225 $ 160 $ 730 $ 762 Research and development 20,251 15,366 57,588 43,949 Selling, general and administrative 15,285 11,464 42,695 33,719 Total stock-based compensation expense $ 35,761 $ 26,990 $ 101,013 $ 78,430

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2022
Earnings Per Share [Abstract]
Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share	The following weighted-average outstanding common stock equivalents were excluded from the computation of diluted net loss per share for the periods presented because including them would have been antidilutive: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Options to purchase common stock, 11,969,532 8,287,010 11,114,822 8,287,394 Employee stock purchase plan 44,649 30,196 15,047 16,923 12,014,181 8,317,206 11,129,869 8,304,317

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 30, 2022
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Total Accumulated Other Comprehensive Loss	Total accumulated other comprehensive loss consisted of the following (in thousands): September 30, December 31, 2022 2021 Foreign currency translation adjustments $ ( 1,332 ) $ ( 121 ) Unrealized loss on available-for-sale securities ( 8,890 ) ( 1,283 ) Total accumulated other comprehensive loss $ ( 10,222 ) $ ( 1,404 )

Organization - Additional Infor

Organization - Additional Information (Details)	9 Months Ended
	Sep. 30, 2022 Segment
United States of America
Organization And Nature Of Business [Line Items]
Number of reportable segments	1

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 391,651	$ 307,584	$ 197,538
Restricted cash included in prepaid expenses and other current assets	$ 517		$ 10,000
Restricted Cash and Cash Equivalents, Current, Asset, Statement of Financial Position [Extensible List]	Prepaid expenses and other current assets		Prepaid expenses and other current assets
Restricted cash included in other assets	$ 4,140		$ 2,001
Restricted Cash and Cash Equivalents, Noncurrent, Asset, Statement of Financial Position [Extensible List]	Other assets		Other assets
Total cash, cash equivalents, and restricted cash shown in the statements of cash flows	$ 396,308	$ 309,585	$ 209,539	$ 726,294

Financial Instruments - Summary

Financial Instruments - Summary of Financial Assets Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	$ 990,189	$ 1,001,451
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	387,427	298,965
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	602,762	702,486
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	357,285	266,765
Money Market Funds | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	357,285	266,765
Asset-backed Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	0	41,245
Asset-backed Securities | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	0	41,245
Certificate of Deposits and Time Deposits
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	29,100	16,000
Certificate of Deposits and Time Deposits | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	29,100	16,000
Corporate Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	380,957	349,691
Corporate Bonds | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	380,957	349,691
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	82,137	187,624
Commercial Paper | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	82,137	187,624
U.S. Government Treasury and Agency Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	109,839	87,435
U.S. Government Treasury and Agency Securities | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	19,081
U.S. Government Treasury and Agency Securities | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	90,758	87,435
Debt Securities in Government Sponsored Entities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	15,747	19,549
Debt Securities in Government Sponsored Entities | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	15,747	19,549
Investments in Arcturus and Solid Common Stock
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	11,061	32,200
Investments in Arcturus and Solid Common Stock | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	11,061	32,200
Other
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	4,063	942
Other | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	$ 4,063	$ 942

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Cash Equivalents and Investments Classified as Available For Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 983,955	$ 969,592
Gross Unrealized Gains	8	5
Gross unrealized losses	(8,898)	(1,288)
Estimated Fair Value	975,065	968,309
Money Market Funds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	357,285	266,765
Estimated Fair Value	357,285	266,765
Asset-backed Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	0	41,282
Gross Unrealized Gains		1
Gross unrealized losses	0	(38)
Estimated Fair Value	0	41,245
Certificate of Deposits and Time Deposits
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	29,100	16,000
Estimated Fair Value	29,100	16,000
Corporate Bonds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	388,158	350,667
Gross Unrealized Gains		3
Gross unrealized losses	(7,201)	(979)
Estimated Fair Value	380,957	349,691
Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	82,137	187,624
Estimated Fair Value	82,137	187,624
U.S. Government Treasury and Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	111,248	87,642
Gross Unrealized Gains	8	1
Gross unrealized losses	(1,417)	(208)
Estimated Fair Value	109,839	87,435
Debt Securities in Government Sponsored Entities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	16,027	19,612
Gross unrealized losses	(280)	(63)
Estimated Fair Value	$ 15,747	$ 19,549

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) $ in Millions	9 Months Ended
	Sep. 30, 2022 USD ($) CorporateBondSecurities
Corporate Bonds
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, unrealized loss position, twelve months or longer, fair value	$ 77.7
Available for sale securities unrealized loss position accumulated loss	$ 1.7
Number of available-for-sale securities unrealized loss position twelve months or longer | CorporateBondSecurities	30
Maximum
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities remaining contractual maturities	3 years

Balance Sheet Components - Su_2

Balance Sheet Components - Summary of Inventory (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Work-in-process	$ 15,777	$ 10,504
Finished goods	6,072	5,727
Total inventory	$ 21,849	$ 16,231

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Research, clinical study, and manufacturing expenses	$ 61,921	$ 40,880
Payroll and related expenses	67,197	62,591
Other	59,933	42,084
Total accrued liabilities	$ 189,051	$ 145,555

Revenue - Summary of Disaggrega

Revenue - Summary of Disaggregation of Total Revenues from Customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Total revenues
Total revenues	$ 90,703	$ 81,647	$ 259,981	$ 268,017
Collaboration and License
Total revenues
Total revenues	52,827	55,048	154,328	197,998
Collaboration and License | Crysvita
Total revenues
Total revenues	51,348	42,971	148,121	120,987
Collaboration and License | Royalty Revenue in European Territory | Crysvita
Total revenues
Total revenues	0	16	0	244
Collaboration and License | Daiichi Sankyo
Total revenues
Total revenues	1,479	12,061	6,207	76,767
Product Sales
Total revenues
Total revenues	32,503	21,950	90,019	56,809
Product Sales | Crysvita
Total revenues
Total revenues	13,184	7,378	34,980	16,150
Product Sales | Mepsevii
Total revenues
Total revenues	6,045	3,918	15,839	12,924
Product Sales | Dojolvi
Total revenues
Total revenues	13,274	10,654	39,200	27,735
Non-cash Collaboration Royalty Revenue
Total revenues
Total revenues	5,373	4,649	15,634	13,210
Non-cash Collaboration Royalty Revenue | Crysvita
Total revenues
Total revenues	$ 5,373	$ 4,649	$ 15,634	$ 13,210

Revenue - Summary of Disaggre_2

Revenue - Summary of Disaggregation of Total Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation Of Revenue [Line Items]
Total revenues	$ 90,703	$ 81,647	$ 259,981	$ 268,017
U.S. and Canada [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	67,012	66,911	196,257	230,220
Europe
Disaggregation Of Revenue [Line Items]
Total revenues	8,411	7,244	26,114	19,581
Latin America
Disaggregation Of Revenue [Line Items]
Total revenues	14,119	7,492	36,449	18,216
Japan
Disaggregation Of Revenue [Line Items]
Total revenues	$ 1,161	$ 0	$ 1,161	$ 0

Revenue - Summary of Changes in

Revenue - Summary of Changes in Contract Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Abstract]
Balance of contract liabilities at beginning of period	$ (9,076)	$ (66,568)
Additions	(89)	(2,390)
Deductions	6,207	76,767
Balance of contract assets (liabilities) at end of period	$ (2,958)	$ 7,809

Revenue - Additional Informatio

Revenue - Additional Information (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Disaggregation of Revenue [Abstract]
Percentage of gross accounts receivable balance	49%	71%
Percentage of gross accounts receivable balance from different customer	16%	0%

GeneTx Acquisition - Additional

GeneTx Acquisition - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended	9 Months Ended
	Jul. 31, 2022	Apr. 30, 2022	Aug. 31, 2019	Sep. 30, 2022	Sep. 30, 2022	Sep. 30, 2021
Business Acquisition [Line Items]
Net of cash and working capital acquired					$ 75,391	$ 0
Acquired in-process research and development					$ 75,234	$ 0
GeneTx [Member]
Business Acquisition [Line Items]
Business acquisition, consideration transferred	$ 75,000
Regulatory Approval Milestones	85,000
Outstanding Cash and Cash Equivalents Acquired	15,600
Amount on Adjustments for Working Capital and Transaction Expenses	600
Payments to Acquire Businesses, Gross	91,200
GeneTx [Member] | Maximum [Member]
Business Acquisition [Line Items]
Future contingent milestone payments	190,000
Additional Milestone Payments	30,000
Commercial Milestone Payment	$ 75,000
In Process Research and Development [Member] | GeneTx [Member]
Business Acquisition [Line Items]
Acquired in-process research and development				$ 75,200
Gene Tx Biotherapeutics L L C [Member] | Program Agreement And Unitholder Option Agreement [Member]
Business Acquisition [Line Items]
Business acquisition option exercise period, description					the Company made an upfront payment of $20.0 million for an exclusive option to acquire GeneTx, which was exercisable any time prior to 30 days following FDA acceptance of the IND for GTX-102.
Upfront payment for exclusive option to acquisition			$ 20,000
Option extension Premium			$ 25,000
Acquisition cost		$ 75,000

License and Research Agreemen_3

License and Research Agreements - Additional Information (Details) - USD ($)

1 Months Ended

3 Months Ended

9 Months Ended

113 Months Ended

Jan. 01, 2023

Jul. 01, 2022

Apr. 30, 2022

Jan. 31, 2022

May 31, 2021

Jan. 31, 2021

Mar. 31, 2020

Aug. 31, 2019

Sep. 30, 2022

Sep. 30, 2021

Mar. 31, 2021

Mar. 31, 2020

Sep. 30, 2022

Sep. 30, 2021

Dec. 31, 2022

Dec. 31, 2021

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Collaboration and license revenue

$ 90,703,000

$ 81,647,000

$ 259,981,000

$ 268,017,000

Daiichi Sankyo

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Deferred revenue

3,000,000

3,000,000

$ 9,100,000

Revenue recognized

1,500,000

6,200,000

Revenue recognized

12,100,000

76,800,000

Receivable related to Daiichi Sankyo license agreement

0

$ 0

100,000

Regeneron

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Upfront payments of collaboration

$ 30,000,000

Intangible assets, remaining amortization period

10 years 6 months

Eligible future milestone payments

$ 63,000,000

Costs of goods sold related to amortization of intangible asset

700,000

$ 2,100,000

Development costs

2,500,000

4,300,000

Sales

0

$ 0

Regeneron | Maximum

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Profit loss sharing percentage on net sales

40%

Regeneron | Minimum

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Profit loss sharing percentage on net sales

20%

Abeona

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Development and transition costs

800,000

$ 2,900

Abeona | Maximum

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Eligible future milestone payments

1,000

1,000

Product Sales

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Collaboration and license revenue

32,503,000

21,950,000

$ 90,019,000

56,809,000

License and Collaboration Agreement | Mereo

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Upfront payment for in-process research and development expense

$ 50,000,000

Payments made under agreement

$ 50,000,000

License and Collaboration Agreement | Maximum | Mereo

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Future contingent milestone payments

$ 254,000,000

License and Collaboration Agreement | Abeona

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Percentage of royalty on net sales receives

10%

Commercial milestone payments

$ 30,000,000

Kyowa Kirin Collaboration | License Agreement | Prepaid Expenses and Other Current Assets

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

License agreement other receivables

3,200,000

$ 3,200,000

16,000,000

Kyowa Kirin Collaboration | License Agreement | Product Sales

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Collaboration and license revenue

13,200,000

7,400,000

35,000,000

16,200,000

Kyowa Kirin Collaboration | License Agreement | Profit Share Revenue

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

License agreement accounts receivable

15,200,000

15,200,000

20,200,000

Kyowa Kirin Collaboration | License Agreement | Commercial and Development Activity Reimbursements

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

License agreement accrued liabilities

5,100,000

$ 5,100,000

$ 2,300,000

Kyowa Kirin Collaboration | License Agreement | Scenario Forecast

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Profit loss sharing percentage on net sales

30%

35%

Kyowa Kirin Collaboration | License Agreement | Profit Share Territory

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Percentage of right to receive royalty payments on net sales

30%

Remaining profit or loss share percentage on commercializing products

50%

Kyowa Kirin Collaboration | License Agreement | Profit Share Territory | Maximum

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Tiered double-digit revenue share percentage entitled to receive

30%

Kyowa Kirin Collaboration | License Agreement | Profit Share Territory | Minimum

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Tiered double-digit revenue share percentage entitled to receive

20%

Kyowa Kirin Collaboration | License Agreement | Royalty Revenue in European Territory

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Percentage of royalty on net sales receives

10%

Program Agreement and Unitholder Option Agreement | GeneTx Biotherapeutics LLC

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Upfront payment for exclusive option to acquisition

$ 20,000,000

Business acquisition option exercise period, description

the Company made an upfront payment of $20.0 million for an exclusive option to acquire GeneTx, which was exercisable any time prior to 30 days following FDA acceptance of the IND for GTX-102.

Option extension Premium

$ 25,000,000

Acquisition cost

$ 75,000,000

License and Technology Access Agreement | Daiichi Sankyo

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Upfront payment received

$ 125,000,000

Deferred revenue

$ 25,000,000

25,000,000

Premium from stock purchase agreement

19,700,000

Transaction price of license agreement

183,400,000

Estimated reimbursement of delivering license and technology services

5,700,000

License and Technology Access Agreement | PCL and HEK293 Platform | Daiichi Sankyo

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Deferred revenue

$ 25,000,000

$ 25,000,000

License and Technology Access Agreement | License Agreement | Daiichi Sankyo

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Revenue recognized

180,400,000

Stock Purchase Agreement | Daiichi Sankyo

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Issuance of common stock in connection with license agreement, net of issuance costs, shares

1,243,913

Proceeds from issuance of common stock in connection with license agreement

$ 75,000,000

Issuance of common stock in connection with license agreement, net of issuance costs

$ 55,300,000

Stock price

$ 44.43

$ 44.43

Premium from stock purchase agreement

$ 19,700,000

Sublicense Agreement | Daiichi Sankyo

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Upfront payment received

$ 8,000,000

License and Research Agreemen_4

License and Research Agreements - Share of Collaboration and Royalty Revenue Related to Crysvita (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	$ 90,703	$ 81,647	$ 259,981	$ 268,017
Collaboration and Royalty | Kyowa Kirin Collaboration
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	56,721	47,636	163,755	134,441
Collaboration and Royalty | Kyowa Kirin Collaboration | Profit Share Territory
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	51,348	42,971	148,121	120,987
Collaboration and Royalty | Kyowa Kirin Collaboration | Royalty Revenue in European Territory
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	0	16	0	244
Non-cash Collaboration Royalty Revenue
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	5,373	4,649	15,634	13,210
Non-cash Collaboration Royalty Revenue | Kyowa Kirin Collaboration | Royalty Revenue in European Territory
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	$ 5,373	$ 4,649	$ 15,634	$ 13,210

License and Research Agreemen_5

License and Research Agreements - Schedule of Cost Sharing Payments (Details) - Kyowa Kirin Collaboration - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Cost Sharing Payments [Line Items]
Research and development	$ 3,830	$ 5,161	$ 12,770	$ 16,517
Selling, general and administrative	8,365	8,005	26,510	23,076
Total	$ 12,195	$ 13,166	$ 39,280	$ 39,593

License and Research Agreemen_6

License and Research Agreements - Schedule of Changes in Fair Value of Equity Investment (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, Beginning balance	$ 1,001,451
Common stock, Ending balance	990,189	$ 1,001,451
Solid and Arcturus | Common Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, Beginning balance	32,200	154,756
Common stock, Change in fair value	(21,139)	(42,713)
Common stock, Sale of shares		(79,843)
Common stock, Ending balance	$ 11,061	$ 32,200

Liability Related to the Sale_3

Liability Related to the Sale of Future Royalties - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended		9 Months Ended
	Jul. 31, 2022	Dec. 31, 2019	Sep. 30, 2022	Sep. 30, 2021
Liability Related To Sale Of Future Royalties [Line Items]
Net proceeds from sale of future royalties in 2019			$ 490,950	$ 0
OMERS
Liability Related To Sale Of Future Royalties [Line Items]
Net proceeds from sale of future royalties in 2019			$ 490,950
Royalty Purchase Agreement
Liability Related To Sale Of Future Royalties [Line Items]
Profit loss sharing percentage on net sales	30%
Royalty Purchase Agreement | RPI Finance Trust (RPI)
Liability Related To Sale Of Future Royalties [Line Items]
Proceeds from sale of future royalties		$ 320,000
Royalty payment termination description			The agreement with RPI will automatically terminate, and the payment of royalties to RPI will cease, in the event aggregate royalty payments received by RPI are equal to or greater than $608.0 million prior to December 31, 2030, or in the event aggregate royalty payments received by RPI are less than $608.0 million prior to December 31, 2030, when aggregate royalty payments received by RPI are equal to $800.0 million
Royalties transaction costs net		5,800
Net proceeds from sale of future royalties in 2019		314,200
Effective annual interest rate			9.60%
Royalty Purchase Agreement | OMERS
Liability Related To Sale Of Future Royalties [Line Items]
Proceeds from sale of future royalties		500,000
Royalty payment termination description	In July 2022, the Company entered into a Royalty Purchase Agreement with OMERS. Pursuant to the agreement, OMERS paid $500.0 million to the Company in consideration for the right to receive 30% of the future royalty payments due to the Company from KKC based on net sales of Crysvita in the U.S. and Canada under the terms of the KKC Collaboration Agreement. The calculation of royalty payments to OMERS will be based on net sales of Crysvita beginning in April 2023 and will expire upon the earlier of the date on which aggregate payments received by OMERS equals $725.0 million or the date the final royalty payment is made to the Company under the KKC Collaboration Agreement.
Royalty agreement termination threshold amount	$ 725,000
Payment from sale of future royalties	$ 500,000
Royalties transaction costs net		9,100
Net proceeds from sale of future royalties in 2019		491,000
Effective annual interest rate			8.30%
Royalty Purchase Agreement | Minimum | RPI Finance Trust (RPI)
Liability Related To Sale Of Future Royalties [Line Items]
Royalty agreement termination threshold amount		608,000
Royalty Purchase Agreement | Maximum | RPI Finance Trust (RPI)
Liability Related To Sale Of Future Royalties [Line Items]
Royalty agreement termination threshold amount		$ 800,000

Liability Related to the Sale_4

Liability Related to the Sale of Future Royalties - Schedule of Activity Within Liability Related to Sale of Future Royalties (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Liability Related To Sale Of Future Royalties [Line Items]
Liabilities related to the sale of future royalties at beginning of year	$ 351,786	$ 335,665	$ 335,665
Net proceeds from sale of future royalties in 2019	490,950	0
Non-cash collaboration royalty revenue	(15,634)	(13,210)	(17,951)
Non-cash interest expense	34,961		34,072
Liabilities related to the sale of future royalties at end of year	862,063		351,786
R P I Finance Trust [Member]
Liability Related To Sale Of Future Royalties [Line Items]
Liabilities related to the sale of future royalties at beginning of year	351,786	$ 335,665	335,665
Non-cash collaboration royalty revenue	(15,634)		(17,951)
Non-cash interest expense	26,247		34,072
Liabilities related to the sale of future royalties at end of year	362,399		$ 351,786
OMERS [Member]
Liability Related To Sale Of Future Royalties [Line Items]
Net proceeds from sale of future royalties in 2019	490,950
Non-cash interest expense	8,714
Liabilities related to the sale of future royalties at end of year	$ 499,664

Stock-Based Awards - Additional

Stock-Based Awards - Additional Information (Details)	9 Months Ended
	Sep. 30, 2022 shares
2014 Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share reserved for future issuance	2,034,566
Automatic increases in shares available for grant effective date	Jan. 01, 2015
Shares available for grant, ending date	Jan. 01, 2024
2014 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share reserved for future issuance	4,640,287
Employment Inducement Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share reserved for future issuance	322,697

Stock-Based Awards - Summary of

Stock-Based Awards - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 35,761	$ 26,990	$ 101,013	$ 78,430
Cost of sales
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	225	160	730	762
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	20,251	15,366	57,588	43,949
Selling, general and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 15,285	$ 11,464	$ 42,695	$ 33,719

Net Loss Per Share - Outstandin

Net Loss Per Share - Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock equivalents excluded from computation of diluted net loss per share	12,014,181	8,317,206	11,129,869	8,304,317
Options to Purchase Common Stock, RSUs, and PSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock equivalents excluded from computation of diluted net loss per share	11,969,532	8,287,010	11,114,822	8,287,394
Employee Stock Purchase Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock equivalents excluded from computation of diluted net loss per share	44,649	30,196	15,047	16,923

Equity Transactions - Additiona

Equity Transactions - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	May 31, 2021	Sep. 30, 2022	Sep. 30, 2022
Stockholders Equity [Line Items]
Stock sold in at-the-market offering			1,050,372
Net proceeds from at-the-market offering			$ 78.9
Open Market Sale
Stockholders Equity [Line Items]
Common stock shares sold		0	0
Option to sell common stock aggregate offering price	$ 350

Related Party Transaction - Add

Related Party Transaction - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Related Party Transaction [Line Items]
Research and development		$ 237,297	$ 113,417	$ 534,981	$ 374,140
Contribution amount paid	$ 1,000
Contribution period	4 years
Non Profit Foundation Member | Rare Disease Education And Awareness Member
Related Party Transaction [Line Items]
Research and development		$ 300		$ 300

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income - Schedule of Total Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustments	$ (1,332)	$ (121)
Unrealized loss on available-for-sale securities	(8,890)	(1,283)
Total accumulated other comprehensive loss	$ (10,222)	$ (1,404)