Commitments and Contingencies - Other (Details)		3 Months Ended
	Jan. 30, 2019 USD ($) ft²	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Mar. 15, 2019 USD ($)
Commitments and Contingencies
Area of office space (in square feet) | ft²	14,075
Period for which base rent is abated	10 months
Annual base rent per month after abatement	$ 19,650
Percentage of annual increase in lease rent	3.00%
Executed letter of credit	$ 39,000
Total remaining commitment under the amended and restated sublease				$ 2,700,000
Rent expenses operating leases		$ 103,000	$ 100,000