Commitments (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) ft²	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) ft²	Sep. 30, 2018 USD ($)
Maturity analysis of undiscounted cash flows of operating lease liabilities
2019	$ 360		$ 360
2020	721		721
Total minimum lease payments	1,081		1,081
Rent expense	100	$ 300	200	$ 1,000
Lease payments	400	$ 300	1,100	$ 1,000
Sublease
Future sublease income to be received in the remainder of 2019	300		300
Future sublease income to be received in 2020	500		500
Sublease income received	$ 300		$ 800
Leased space (in square feet) | ft²	11,472		11,472
Aggregate rent obligation under sublease			$ 1,900