Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues:
Products, net		$ 121,429	$ 99,041	$ 333,221	$ 280,720
Type of Revenue [Extensible List]				us-gaap:ProductMember	us-gaap:ProductMember
Collaboration		22,495		$ 61,740
Total revenues		143,924	99,041	394,961	$ 280,720
Cost and expenses:
Cost of sales (excluding amortization of in-licensed rights)		15,015	13,037	40,978	41,019
Research and development		190,438	133,949	515,104	337,768
Selling, general and administrative		75,373	75,429	231,829	203,388
Acquired in-process research and development					173,240
Amortization of in-licensed rights		166	216	497	649
Total cost and expenses		280,992	222,631	788,408	756,064
Operating loss		(137,068)	(123,590)	(393,447)	(475,344)
Other (loss) income:
Gain from sale of Priority Review Voucher				108,069
Loss on contingent consideration	[1]	(45,000)		(45,000)
Other expense, net		(14,335)	(2,510)	(34,202)	(3,544)
Total other (loss) income		(59,335)	(2,510)	28,867	(3,544)
Loss before income tax expense		(196,403)	(126,100)	(364,580)	(478,888)
Income tax expense		96	226	231	484
Net loss		(196,499)	(126,326)	(364,811)	(479,372)
Other comprehensive (loss) income:
Unrealized (losses) gains on investments, net of tax		(12)	(7)	(56)	174
Total other comprehensive (loss) income		(12)	(7)	(56)	174
Comprehensive loss		$ (196,511)	$ (126,333)	$ (364,867)	$ (479,198)
Net loss per share - basic and diluted		$ (2.50)	$ (1.70)	$ (4.70)	$ (6.54)
Weighted average number of shares of common stock used in computing basic and diluted net loss per share		78,501	74,177	77,637	73,298

[1] The loss on contingent consideration is related to the fair value adjustment of the regulatory-related contingent payments that are accounted for as derivatives. Please see Note 5. Fair Value Measurements for further details.