License Agreements - Merus (Details) $ / shares in Units, $ in Thousands	1 Months Ended			3 Months Ended		6 Months Ended		67 Months Ended
	Jan. 31, 2022 item	Jan. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) item $ / shares shares	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
License agreements
Long term investments				$ 149,784		$ 149,784		$ 149,784	$ 221,266
Research and development expense				347,196	$ 343,511	700,569	$ 650,407
Unrealized gain (loss) on long term investments				(24,897)	26,765	(71,482)	(944)
Total revenues				911,397	705,709	1,644,632	1,310,427
Net income						199,424	202,991
Current assets				3,625,845		3,625,845		3,625,845	3,118,674
Current liabilities				926,674		926,674		926,674	854,308
Merus
License agreements
Fair market value of our long term investments				$ 80,400		$ 80,400		$ 80,400	$ 112,900
Ownership percentage (as a percent)				8.00%		8.00%		8.00%
Unrealized gain (loss) on long term investments				$ (13,500)	$ 600	$ (32,500)	$ 10,000
Merus | IPO
License agreements
Common shares purchased (in shares) | shares		350,000
Number of shares in underwritten public offering (in shares) | shares		4,848,485
Per share price | $ / shares		$ 24.75
Value of shares acquired		$ 8,700
Merus
License agreements
Number of independent programs | item			10
Number of additional preclinical discovery programs | item	10
Number of programs under the resulting products are co-funded for development | item	2
Associated future global development costs , if elected to co-develop (as a percent)	35.00%
Milestone payment made under license agreement								$ 2,000
Merus | U.S.
License agreements
Profit sharing (as a percent)			50.00%
Percentage of profit (losses)			50.00%
Merus | Minimum
License agreements
Royalty payments on future global net sales (as a percent)			6.00%
Merus | Minimum | Non-U.S.
License agreements
Royalty payments on future global net sales (as a percent)			6.00%
Merus | Maximum
License agreements
Royalty payments on future global net sales (as a percent)			10.00%
Merus | Maximum | U.S.
License agreements
Royalty payments on future global net sales (as a percent)			4.00%
Merus | Maximum | Non-U.S.
License agreements
Royalty payments on future global net sales (as a percent)			10.00%
Merus | Maximum | Development and Regulatory Milestones
License agreements
Additional milestone payments under the license agreement			$ 100,000
Merus | Maximum | Commercialization Milestones
License agreements
Additional milestone payments under the license agreement			$ 250,000
Stock purchase agreement | Merus
License agreements
Purchase of common stock under Stock Purchase Agreement (in shares ) | shares			3,200,000
Purchase price of common stock			$ 80,000
Per share price | $ / shares			$ 25.00