Collaborative Arrangements - Merck Platform Technology Transfer and License Agreement (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Aug. 31, 2015
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized	$ 14,967,000	$ 12,319,000	$ 29,637,000	$ 27,901,000
Contract with customer, liability	5,045,000		5,045,000		$ 2,044,000
Merck [Member] | Technology Transfer, Collaboration and License Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized	200,000	1,000,000.0	1,000,000.0	2,000,000.0
Contingent receivable						$ 15,000,000.0
Merck [Member] | Technology Transfer, Collaboration and License Agreement [Member] | License Fee [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized		$ 900,000		$ 900,000
Merck [Member] | Technology Transfer, Collaboration and License Agreement [Member] | Maintenance [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized	25,000		50,000
Contract with customer, liability	$ 100,000		$ 100,000		$ 0