Revenues - Narrative (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($) agreement	Jun. 30, 2019 USD ($) agreement
Summary Of Deferred Revenue [Line Items]
Contract revenue recognized		$ 3,054
Minimum
Summary Of Deferred Revenue [Line Items]
Payment terms, range		30 days
Maximum
Summary Of Deferred Revenue [Line Items]
Payment terms, range		45 days
Nippon Shinyaku
Summary Of Deferred Revenue [Line Items]
Number of license, development and commercialization agreements | agreement	2	2
Contract revenue recognized	$ 1,200	$ 3,100
Revenue, performance obligation, description of timing		The deferred revenue balances are being recognized over an average of four years representing the period over which we expect to perform our research and developments obligations under each agreement.