Commitments and Contingencies - Other Information Related to Leases (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Commitments and Contingencies
Cash paid for amounts included in the measurement of operating lease liabilities	$ 477
Right-to-use assets obtained in exchange for new finance lease liabilities	$ 15
Weighted-average remaining lease term - finance leases	3 years 2 months 19 days
Weighted-average remaining lease term - operating leases	2 years 6 months 11 days
Weighted-average discount rate - finance leases	6.88%
Weighted-average discount rate - operating leases	6.29%