Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (447,510)	$ (224,076)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in fair value of contingent consideration	416	(4,763)
Depreciation and amortization	11,353	9,430
Stock-based compensation expense	73,687	84,822
(Gain) loss on equity securities	(28,286)	3,343
Excess inventory reserve	15,084	0
Other non-cash items	6,228	(1,841)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	13,923	(9,347)
Inventory	(17,404)	(4,466)
Operating lease right-of-use assets	15,074	11,085
Accounts payable	7,475	(14,042)
Accrued expenses and other liabilities	20,276	(14,025)
Operating lease liabilities	(16,468)	(10,131)
Deferred revenue	367	11,412
Collaboration research advancement	(3,190)	(3,779)
Net cash used in operating activities	(348,975)	(166,378)
Cash flows from investing activities:
Purchase of property, plant and equipment	(9,204)	(15,478)
Purchases of marketable securities	(196,145)	(101,421)
Proceeds from maturities of marketable securities	557,751	580,875
Proceeds from sales of marketable securities	31,318	29,878
Purchase of intangible assets	(2,000)	0
Net cash provided by investing activities	381,720	493,854
Cash flows from financing activities:
Proceeds from public offering of common stock, net of issuance costs	0	541,536
Proceeds from exercise of stock options and ESPP contributions	4,192	2,549
Net cash provided by financing activities	4,192	544,085
Increase in cash, cash equivalents and restricted cash	36,937	871,561
Cash, cash equivalents and restricted cash at beginning of period	373,728	381,709
Cash, cash equivalents and restricted cash at end of period	410,665	1,253,270
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	353,468	1,198,768
Restricted cash included in receivables and other current assets	2,687	0
Restricted cash included in restricted cash and other non-current assets	54,510	54,502
Total cash, cash equivalents and restricted cash	410,665	1,253,270
Supplemental cash flow disclosures from investing and financing activities:
Purchases of property, plant and equipment included in accounts payable and accrued expenses	1,508	1,257
Right-of-use assets obtained in exchange for operating lease liabilities	22,049	14,663
Issuance of unrestricted stock awards to settle accrued employee compensation	$ 12,013	$ 0