Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities:
Net (loss) income	$ (616,433)	$ (404,734)	$ 397,555
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Acquired in-process research and development	70,000	0	0
Depreciation and amortization	3,872	3,858	3,233
Deferred income taxes	0	0	110,333
Share-based compensation	70,373	59,920	53,047
Gain from Longboard equity method investment	(13,869)	(12,955)	0
Amortization of original issue discounts, net of premiums, on available- for-sale investments	4,247	1,550	(5,628)
Other operating activities, net	6,615	754	3,946
Changes in operating assets and liabilities:
Accounts receivable	1,101	344	3,432
Prepaid expenses and other assets	16,460	(12,602)	(8,133)
Accounts payable, accrued clinical and other current liabilities	5,618	10,771	10,909
Net cash (used in) provided by operating activities - continuing operations	(452,016)	(353,094)	568,694
Investing activities:
Cash paid for acquired in-process research and development	(70,000)	0	0
Purchases of available-for-sale investments	(612,218)	(1,033,665)	(1,469,220)
Proceeds from sale and maturity of available-for-sale investments	1,004,607	1,014,083	976,093
Purchases of property and equipment	(988)	(820)	(4,819)
Other non-current assets	0	(1,000)	0
Net cash provided by (used in) investing activities - continuing operations	321,401	(21,402)	(497,946)
Net cash provided by investing activities - discontinued operations	0	0	997
Net cash provided by (used in) investing activities	321,401	(21,402)	(496,949)
Financing activities:
Principal payments on lease financing obligations	(4,401)	(3,815)	(3,282)
Proceeds from issuance of common stock under ATM facility, net	98,438	0	0
Proceeds from issuance of common stock in public offering, net	0	301,819	0
Proceeds from issuance of common stock from stock plans, net	41,370	52,602	13,147
Net cash provided by financing activities	135,407	350,606	9,865
Effect of exchange rate changes on cash	236	160	(10)
Net increase in cash, cash equivalents and restricted cash	5,028	(23,730)	81,600
Cash, cash equivalents and restricted cash at beginning of year	219,770	243,500	161,900
Cash, cash equivalents and restricted cash at end of year	224,798	219,770	243,500
Supplemental disclosure of cash flow information:
Interest paid	$ 4,077	$ 4,458	$ 4,787