Collaborative Arrangements and Licensing Agreements, Roche (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended								12 Months Ended
	Jan. 31, 2018	Apr. 30, 2013	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue earned			$ 172,299	$ 120,911	$ 104,152	$ 110,304	$ 160,349	$ 110,927	$ 38,470	$ 36,874	$ 507,666	$ 346,620	$ 283,703
Roche [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Upfront payment recorded as deferred revenue		$ 30,000
Milestone payments received											3,000
Maximum amount of payments receivable for license fees and substantive milestones			365,000								365,000
Maximum amount of payments receivable for development milestones			70,000								70,000
Maximum amount of payments receivable for regulatory milestones			170,000								170,000
Maximum amount of payments receivable for commercialization milestones			80,000								80,000
Maximum amount of payment receivable for each additional drug developed			136,500								136,500
Cumulative payments received			60,000								60,000
Next prospective milestone			$ 10,000								10,000
Revenue earned											$ 53,000	7,100	$ 31,200
Deferred revenue							$ 1,700					$ 1,700
Roche [Member] | Revenue [Member] | Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage											10.00%	2.00%	11.00%
Roche [Member] | Subsequent Event [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
License fee received	$ 45,000