Commitments and Contingencies (Details) $ in Thousands		12 Months Ended
	Jul. 31, 2015 ft²	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Lease Arrangements
Loss Contingency Accrual		$ 0
Operating lease obligations
Total		3,507
2019		1,456
2020		507
2021		515
2022		522
2023		507
Other contractual commitments
Total		10,166
2019		10,166
Future minimum contractual obligations and commitments
Total		13,673
2019		11,622
2020		507
2021		515
2022		522
2023		$ 507
Lease Agreement, Business and Research Premises
Lease Arrangements
Termination notice period		6 months
Lease Agreement, Office Premises
Lease Arrangements
Leased office space (in square feet) | ft²	15,000
Lease Agreement, Equipment
Lease Arrangements
Lease expense		$ 1,400	$ 1,300	$ 1,300