Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue:
Total revenue	$ 27,762	$ 152,928	$ 1,153,497	$ 212,245
Operating costs and expenses:
Research and development	102,895	65,714	290,653	187,032
General and administrative	18,718	12,055	57,666	40,027
Total operating costs and expenses	126,396	83,443	365,270	247,853
Income (loss) from operations	(98,634)	69,485	788,227	(35,608)
Non-operating income (expense):
Interest expense	(5,442)	(5,540)	(16,167)	(16,452)
Non-cash interest expense on liability related to sale of future royalties	(4,814)	(4,471)	(14,808)	(13,535)
Interest income and other income (expense), net	11,847	1,599	25,523	3,163
Total non-operating income (expense), net	1,591	(8,412)	(5,452)	(26,824)
Income (loss) before provision for income taxes	(97,043)	61,073	782,775	(62,432)
Provision for income taxes	(900)	202	3,250	434
Net income (loss)	$ (96,143)	$ 60,871	$ 779,525	$ (62,866)
Net income (loss) per share
Basic	$ (0.56)	$ 0.39	$ 4.63	$ (0.41)
Diluted	$ (0.56)	$ 0.37	$ 4.34	$ (0.41)
Weighted average shares outstanding used in computing net income (loss) per share:
Basic	172,698	156,411	168,363	155,153
Diluted	172,698	162,641	179,619	155,153
Product Sales [Member]
Revenue:
Total revenue	$ 4,256	$ 4,448	$ 16,414	$ 24,897
Operating costs and expenses:
Cost of goods sold	4,783	5,674	16,951	20,794
Royalty Revenue [Member]
Revenue:
Total revenue	10,259	9,302	29,898	23,953
Non-cash Royalty Revenue Related to Sale of Future Royalties [Member]
Revenue:
Total revenue	8,372	8,066	24,337	21,367
License, Collaboration and Other Revenue [Member]
Revenue:
Total revenue	$ 4,875	$ 131,112	$ 1,082,848	$ 142,028