Commitments and Contingencies - Leases (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Lease expense	$ 352	$ 705
Cash payments against operating lease liabilities	327	654
Operating lease right-of-use assets	8,239	8,239
Current portion of lease liabilities	271	271
Total operating lease liabilities	$ 10,409	$ 10,409
Weighted average remaining lease term (years)	12 years 3 months 18 days	12 years 3 months 18 days
Weighted average discount rate	11.00%	11.00%
Non-cash lease expense		$ 130
Change in operating lease liabilities		79
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Year 1	$ 1,405	1,405
Year 2	1,453	1,453
Year 3	1,499	1,499
Year 4	1,523	1,523
Year 5	1,552	1,552
Thereafter	12,117	12,117
Total lease payments	19,549	19,549
Less imputed interest	(9,140)	(9,140)
Total	10,409	10,409
Other long-term liabilities	$ 10,138	$ 10,138	$ 2,119