Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Mar. 31, 2019 USD ($) ft²	Jan. 01, 2019 USD ($)
Leases
Lease to eliminate square feet | ft²				16,200
Renewal term (in years)				5 years
Lease, remaining square feet | ft²				33,400
Lease liabilities	$ 3,657
Right-of-use assets	3,473
Operating lease expense	2,500	$ 4,000	$ 4,100
Variable lease expense	1,500	$ 4,000	$ 4,100
Operating lease payments	$ 3,300
Weighted-average remaining lease term	2 years
Weighted-average discount rate	11.00%
Minimum
Leases
Term of lease (in years)	1 year
Maximum
Leases
Term of lease (in years)	6 years
ASC 842
Leases
Term of lease (in years)				3 years
Lease liabilities				$ 1,400	$ 4,700
Right-of-use assets				$ 1,400	$ 3,800