Collaborative Arrangements and Licensing Agreements, AstraZeneca (Details) $ in Thousands	1 Months Ended				3 Months Ended								12 Months Ended
	Feb. 27, 2018 USD ($)	Dec. 31, 2016 USD ($)	Jul. 31, 2015 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2017 USD ($) Drug	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) AccountingUnit Drug Program	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
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
AstraZeneca [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Deferred revenue		$ 51,500			41,800				$ 51,500				41,800	51,500
Revenue earned													$ 13,800	$ 64,900	$ 6,400
AstraZeneca [Member] | Revenue [Member] | Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage													3.00%	19.00%	2.00%
Cardiometabolic and Renal Diseases [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Upfront payment received			$ 65,000
Number of units of accounting | AccountingUnit													1
Minimum potential amount of payments receivable for license fees and substantive milestones					4,000,000								$ 4,000,000
Maximum amount of payments receivable for development milestones					1,100,000								1,100,000
Maximum amount of payments receivable for regulatory milestones					2,900,000								2,900,000
Cumulative payments received					93,000								93,000
Milestone payment earned		$ 25,000
Next prospective milestone					10,000								10,000
Cardiometabolic and Renal Diseases [Member] | Subsequent Event [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Milestone payment earned	$ 30,000
Oncology [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Minimum potential amount of payments receivable for license fees and substantive milestones					750,000								750,000
Maximum amount of payments receivable for development milestones					226,000								226,000
Maximum amount of payments receivable for regulatory milestones					485,000								485,000
Cumulative payments received					97,800								97,800
Milestone payment earned				$ 11,500
Next prospective milestone					17,500								$ 17,500
Number of drugs that can be licensed under option in collaboration agreement | Drug													3
Number of anti-cancer research programs covered by collaboration agreement | Program													3
Cumulative upfront fees received					31,000								$ 31,000
Upfront fee amortized into revenue					11,900								11,900
Deferred revenue					7,600								7,600
Milestone payment to be earned					$ 5,000								$ 5,000
Number of additional drugs that can be developed under research programs covered by collaboration agreement | Drug					2								2