Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended			82 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018
Cash flows from operating activities:
Net income (loss)	$ 681,313	$ (96,692)	$ (153,524)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Non-cash royalty revenue related to sale of future royalties	(33,308)	(30,531)	(30,158)	$ (170,839)
Non-cash interest expense on liability related to sale of future royalties	21,196	18,869	19,712	141,649
Stock-based compensation	88,101	36,615	25,850
Depreciation and amortization	10,870	14,741	15,351
Impairment of equipment from terminated program	0	15,081	0
Accretion of discounts, net, and other non-cash transactions	(10,952)	(881)	(2,185)
Changes in operating assets and liabilities:
Accounts receivable	(25,505)	10,664	4,269
Inventory	(655)	383	237
Other assets	(31,652)	(4,800)	(312)
Accounts payable	971	2,074	518
Accrued compensation	1,674	(10,017)	12,282
Other accrued expenses	27,947	7,277	(71)
Deferred revenue	(15,331)	(28,269)	(17,615)
Other liabilities	3,545	(14,928)	8,622
Net cash provided by (used in) operating activities	718,214	(80,414)	(117,024)
Cash flows from investing activities:
Purchases of investments	(2,271,250)	(404,425)	(334,659)
Maturities of investments	890,957	347,743	253,682
Sales of investments	11,963	37,549	4,969
Purchases of property, plant and equipment	(14,239)	(9,676)	(6,392)
Sales of property and plant	2,633	0	0
Net cash used in investing activities	(1,379,936)	(28,809)	(82,400)
Cash flows from financing activities:
Payment of capital lease obligations	0	(5,131)	(5,945)
Proceeds from shares issued under equity compensation plans	61,735	59,522	20,287
Issuance of common stock, net of issuance costs	790,231	0	189,276
Net cash provided by financing activities	851,966	54,391	203,618
Effect of exchange rates on cash and cash equivalents	(101)	(46)	(124)
Net increase (decrease) in cash and cash equivalents	190,143	(54,878)	4,070
Cash and cash equivalents at beginning of year	4,762	59,640	55,570
Cash and cash equivalents at end of year	194,905	4,762	59,640	$ 194,905
Supplemental disclosure of cash flow information:
Cash paid for interest	19,471	20,116	20,589
Cash paid for income taxes	$ 618	$ 556	$ 757