Commitments and Contingencies - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 457	$ 878
Finance lease cost:
Amortization of right-of-use assets	313	626
Interest on lease liabilities	89	179
Total finance lease cost	402	805
Short-term lease cost	66	173
Variable lease cost	100	132
Total Lease Cost	$ 1,025	$ 1,988