Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (418,780)		$ (554,128)		$ (715,075)
Adjustments to reconcile net loss to cash flows in operating activities:
(Gain) loss on contingent consideration, net	(7,200)	[1]	45,000	[1]
Gain from sale of Priority Review Voucher, net of commission	(102,000)		(108,069)
Depreciation and amortization	38,017		26,911		24,500
Reduction in the carry amounts of the right of use assets	11,325		12,828		6,047
Non-cash interest expense	7,581		25,454		21,444
Stock-based compensation	113,943		108,070		78,602
Impairment of equity investment	4,488
Acquired in-process research and development					173,240
Non-cash up-front payment to StrideBio					29,415
Other	7,620		(2,656)		(7,755)
Changes in operating assets and liabilities, net:
Net increase in accounts receivable	(51,650)		(10,461)		(41,835)
Net increase in inventory	(83,772)		(60,582)		(45,934)
Net decrease (increase) in other assets	103,203		(166,328)		(102,091)
Net (decrease) increase in deferred revenue	(89,244)		749,429
Net increase in accounts payable, accrued expenses, lease liabilities and other liabilities	23,297		41,998		122,979
Net cash (used in) provided by operating activities	(443,172)		107,466		(456,463)
Cash flows from investing activities:
Purchase of property and equipment	(38,490)		(82,202)		(59,631)
Proceeds from sale of Priority Review Voucher	102,000		108,069
Purchase of available-for-sale securities	(29,988)		(1,333,568)		(1,193,632)
Maturity and sales of available-for-sale securities	466,000		1,189,480		1,715,626
Acquisition of Myonexus Therapeutics, Inc., net of cash acquired					(172,556)
Other	(4,109)		(3,500)		(3,082)
Net cash provided by (used in) investing activities	495,413		(121,721)		286,725
Cash flows from financing activities:
Proceeds from sales of common stock, net of offering costs	548,532				365,354
Proceeds from exercise of stock options and purchase of stock under the Employee Stock Purchase Program	20,802		83,957		36,601
Taxes paid related to net share settlement of equity awards	(7,765)		(4,798)		(4,337)
Proceeds from issuance of common stock to Roche, net of offering costs			312,053
Proceeds from term loans			291,150		245,625
Debt issuance costs			(39)		(689)
Net cash provided by financing activities	561,569		682,323		642,554
Increase in cash and cash equivalents	613,810		668,068		472,816
Cash, cash equivalents and restricted cash:
Beginning of year	1,511,713		843,645		370,829
End of year	2,125,523		1,511,713		843,645
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	2,115,869		1,502,648		835,080
Restricted cash in other assets	$ 9,654		$ 9,065		$ 8,565
Restricted Cash, Noncurrent, Asset, Statement of Financial Position [Extensible List]	Other non-current assets		Other non-current assets		Other non-current assets
Total cash, cash equivalents and restricted cash	$ 2,125,523		$ 1,511,713		$ 843,645
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	55,949		34,418		8,550
Cash paid during the period for income taxes	583		2,510		933
Lease liabilities arising from obtaining right of use assets	13,225		59,327
Lease liabilities terminated	40,133
Intangible assets and property and equipment included in accounts payable and accrued expenses	4,162		5,151		1,309
Shares withheld for tax included in accrued expenses	0		6,333		4,798
Accrued debt issuance costs	$ 0		$ 11,000		$ 5,000

[1] The gain (loss) on contingent consideration, net is related to the fair value adjustment of the regulatory-related contingent payments that are accounted for as derivatives. Please see Note 5. Fair Value Measurements for further details.