Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue:
Total revenue	$ 1,087,717	$ 34,589	$ 1,125,735	$ 59,317
Operating costs and expenses:
Research and development	88,334	60,260	187,758	121,318
General and administrative	20,261	15,996	38,948	27,972
Total operating costs and expenses	114,117	85,245	238,874	164,410
Income (loss) from operations	973,600	(50,656)	886,861	(105,093)
Non-operating income (expense):
Interest expense	(5,385)	(5,510)	(10,725)	(10,912)
Non-cash interest expense on liability related to sale of future royalties	(4,975)	(4,512)	(9,994)	(9,064)
Interest income and other income (expense), net	12,105	906	13,676	1,564
Total non-operating income (expense), net	1,745	(9,116)	(7,043)	(18,412)
Income (loss) before provision for income taxes	975,345	(59,772)	879,818	(123,505)
Provision for income taxes	3,885	99	4,150	232
Net income (loss)	$ 971,460	$ (59,871)	$ 875,668	$ (123,737)
Net income (loss) per share
Basic	$ 5.67	$ (0.39)	$ 5.27	$ (0.80)
Diluted	$ 5.33	$ (0.39)	$ 4.91	$ (0.80)
Weighted average shares outstanding used in computing net income (loss) per share:
Basic	171,378	155,352	166,160	154,514
Diluted	182,291	155,352	178,281	154,514
Product Sales [Member]
Revenue:
Total revenue	$ 5,863	$ 15,693	$ 12,158	$ 20,449
Operating costs and expenses:
Cost of goods sold	5,522	8,989	12,168	15,120
Royalty Revenue [Member]
Revenue:
Total revenue	8,563	7,434	19,639	14,651
Non-cash Royalty Revenue Related to Sale of Future Royalties [Member]
Revenue:
Total revenue	9,045	6,638	15,965	13,301
License, Collaboration and Other Revenue [Member]
Revenue:
Total revenue	$ 1,064,246	$ 4,824	$ 1,077,973	$ 10,916