Agreements - Jazz Pharmaceuticals (Details) $ in Thousands	1 Months Ended	3 Months Ended												12 Months Ended
	Aug. 31, 2017 USD ($) item	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Collaborative Agreements disclosures
Revenue from contract with customer		$ 44,864	$ 13,281	$ 15,542	$ 8,584	$ 13,416	$ 10,928	$ 9,287	$ 19,815	$ 39,448	$ 8,480	$ 39,020	$ 28,499	$ 82,271	$ 53,446	$ 115,447
Deferred revenue		127,432				80,802				89,967				127,432	80,802	89,967
Revenue previously deferred														14,817	14,139
Jazz
Collaborative Agreements disclosures
Number of early stage ADC programs | item	2
Potential milestone payment	$ 100,000
Term of agreement	7 years
Offset to research and development expense														12,500	10,000	3,300
Revenue previously deferred														14,500
Upfront payment
Collaborative Agreements disclosures
Deferred revenue	$ 75,000
Upfront payment | Jazz
Collaborative Agreements disclosures
Revenue from contract with customer	$ 75,000
Deferred revenue		60,500												60,500
License and milestone fees
Collaborative Agreements disclosures
Revenue from contract with customer		$ 29,551	$ 79	5,079	79	1,747	672	1,321	11,540	29,580	79	31,080	18,730	34,788	15,280	79,469
Research and development support
Collaborative Agreements disclosures
Revenue from contract with customer				$ 51	$ 17	$ 218	$ 388	$ 388	$ 383	$ 452	$ 650	$ 902	$ 1,478	$ 68	$ 1,377	$ 3,482