Collaborative Arrangements - License Agreement (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Dec. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized		$ 14,967	$ 12,319	$ 29,637	$ 27,901
Roche [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized		$ 200		$ 800
Roche [Member] | Milestone One [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of days for payment	45 days
Roche [Member] | Milestone Two [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of days for payment	60 days