License Agreements - Merus (Details) $ / shares in Units, $ in Thousands	1 Months Ended			3 Months Ended		12 Months Ended	64 Months Ended
	Jan. 31, 2022 item	Jan. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) item $ / shares	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2016 USD ($) $ / shares shares	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
License agreements
Long term investments				$ 174,681			$ 174,681	$ 221,266	[1]
Research and development expense				353,373	$ 306,896
Unrealized gain (loss) on long term investments				(46,585)	(27,709)
Total revenues				733,235	604,718
Net income				37,992	53,535
Current assets				3,288,091			3,288,091	3,118,674	[1]
Current liabilities				886,163			886,163	854,308	[1]
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			$ 100,000
Merus | Maximum | Commercialization Milestones
License agreements
Additional milestone payments under the license agreement			250,000			$ 250,000
Merus
License agreements
Fair market value of our long term investments				$ 93,900			$ 93,900	$ 112,900
Ownership percentage (as a percent)				8.00%			8.00%
Unrealized gain (loss) on long term investments				$ (19,000)	$ 9,400
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 | Stock purchase agreement
License agreements
Purchase of common stock under Stock Purchase Agreement (in shares ) | shares						3,200,000
Purchase price of common stock			$ 80,000			$ 80,000
Per share price | $ / shares			$ 25.00			$ 25.00

[1] The condensed consolidated balance sheet at December 31, 2021 has been derived from the audited consolidated financial statements at that date.