CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (172,530)	$ (139,213)
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation	25,776	21,838
Depreciation and amortization	7,092	3,106
Deferred income taxes	0	(17,425)
Amortization of debt discount and issuance costs	6,518	0
Acquired in-process research and development expense	0	4,500
Change in fair value of contingent consideration liability	1,500	6,100
Other non-cash items, net	833	169
Changes in operating assets and liabilities:
Accounts receivable	(5,662)	(1,309)
Inventory	(1,446)	(1,010)
Prepaid expenses and other current assets	(7,235)	(3,321)
Other non-current assets	(500)	(1,761)
Accounts payable, accrued and other current liabilities	6,585	541
Contingent consideration	(1,500)	0
Operating lease liabilities	(1,293)	(975)
Deferred revenue	(2,313)	(621)
Net cash used in operating activities	(144,175)	(129,381)
Cash flows from investing activities:
Cash paid for in-process research and development asset	0	(4,500)
Purchases of marketable securities	(317,228)	(283,208)
Proceeds from maturities of marketable securities	404,904	232,142
Proceeds from sale of marketable securities	13,500	12,987
Purchases of property and equipment	(87)	(657)
Net cash (used in) provided by investing activities	101,089	(43,236)
Cash flows from financing activities:
Payment of contingent consideration	(18,000)	(15,000)
Proceeds from issuance of common stock under equity incentive plans	1,337	4,589
Payments of tax withholding obligation on vesting restricted stock units	(1,029)	(2,157)
Net proceeds from issuance of convertible senior notes	0	194,000
Proceeds from issuance of common stock, net of issuance costs	0	226,575
Net cash (used in) provided by financing activities	(17,692)	408,007
Net (decrease) increase in cash and cash equivalents	(60,778)	235,390
Cash and cash equivalents, beginning of the period	166,916	62,070
Cash and cash equivalents, end of the period	106,138	297,460
Supplemental disclosure of non-cash investing and financing activities:
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 0	$ 1,156