Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Total revenue	$ 1,193,323	$ 307,711	$ 165,436
Operating costs and expenses:
Cost of goods sold	$ 24,412	$ 30,547	$ 30,215
Type of Cost, Good or Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Research and development	$ 399,536	$ 268,461	$ 203,801
General and administrative	81,443	52,364	44,275
Impairment of equipment and other costs for terminated program	0	15,981	0
Total operating costs and expenses	505,391	367,353	278,291
Income (loss) from operations	687,932	(59,642)	(112,855)
Non-operating income (expense):
Interest expense	(21,582)	(22,085)	(22,468)
Non-cash interest expense on liability related to sale of future royalties	(21,196)	(18,869)	(19,712)
Interest income and other income (expense), net	37,571	4,520	2,387
Total non-operating expense, net	(5,207)	(36,434)	(39,793)
Income (loss) before provision for income taxes	682,725	(96,076)	(152,648)
Provision for income taxes	1,412	616	876
Net income (loss)	$ 681,313	$ (96,692)	$ (153,524)
Net income (loss) per share
Basic	$ 4.02	$ (0.62)	$ (1.10)
Diluted	$ 3.78	$ (0.62)	$ (1.10)
Weighted average shares outstanding used in computing net income (loss) per share
Basic	169,600	155,953	139,596
Diluted	180,119	155,953	139,596
Product Sales [Member]
Revenue:
Total revenue	$ 20,774	$ 32,688	$ 55,354
Royalty Revenue [Member]
Revenue:
Total revenue	41,976	33,527	19,542
Non-cash Royalty Revenue Related to Sale of Future Royalties [Member]
Revenue:
Total revenue	33,308	30,531	30,158
License, Collaboration and Other Revenue [Member]
Revenue:
Total revenue	$ 1,097,265	$ 210,965	$ 60,382