Collaborative Arrangements - Strategic Collaboration Agreement (Details) - USD ($)	1 Months Ended		3 Months Ended			6 Months Ended
	Apr. 30, 2020	Apr. 30, 2018	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract with customer, liability			$ 5,045,000			$ 5,045,000		$ 2,044,000
Revenue recognized			14,967,000	$ 12,319,000		29,637,000	$ 27,901,000
Porton [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized	$ 1,000,000.0		$ 1,000,000.0	$ 0	$ 2,800,000	$ 1,100,000	$ 0
Porton [Member] | Milestone One [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract with customer, liability		$ 500,000
Number of days for payment		30 days
Porton [Member] | Milestone Two [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contingent receivable		$ 1,500,000
Porton [Member] | Milestone Three [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contingent receivable		$ 1,000,000.0