Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Total revenues	$ 169,424	$ 135,291	$ 480,187	$ 352,645
Costs and expenses:
Research and development	140,175	113,606	415,537	346,196
Selling, general and administrative	57,155	39,667	181,629	118,783
Total costs and expenses	214,998	167,488	649,874	503,434
Loss from operations	(45,574)	(32,197)	(169,687)	(150,789)
Investment and other income (loss), net	(21,872)	82,218	66,799	84,460
Net income (loss)	$ (67,446)	$ 50,021	$ (102,888)	$ (66,329)
Net income (loss) per share - basic (in dollars per share)	$ (0.42)	$ 0.35	$ (0.66)	$ (0.46)
Net income (loss) per share - diluted (in dollars per share)	$ (0.42)	$ 0.34	$ (0.66)	$ (0.46)
Shares used in computation of per share amounts - basic (in shares)	159,304	143,357	156,799	142,876
Shares used in computation of per share amounts - diluted (in shares)	159,304	148,068	156,799	142,876
Comprehensive income (loss):
Net income (loss)	$ (67,446)	$ 50,021	$ (102,888)	$ (66,329)
Other comprehensive income (loss):
Unrealized gain (loss) on securities available-for-sale, net of tax of $0, $5,915, $0, and $11,087, respectively	(144)	9,627	(12)	18,044
Foreign currency translation gain (loss)	13	14	(10)	16
Total other comprehensive income (loss)	(131)	9,641	(22)	18,060
Comprehensive income (loss)	(67,577)	59,662	(102,910)	(48,269)
Product [Member]
Revenues:
Total revenues	126,976	79,177	344,776	223,841
Costs and expenses:
Cost of sales	12,348	9,019	35,863	24,555
License and Service [Member]
Revenues:
Total revenues	19,786	39,444	76,524	82,779
Royalty [Member]
Revenues:
Total revenues	22,662	16,670	58,887	46,025
Costs and expenses:
Cost of sales	$ 5,320	$ 5,196	$ 16,845	$ 13,900