Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 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	$ 3,481
Right-of-use assets	3,449	$ 3,473
Operating lease expense	2,300	2,500	$ 4,000
Variable lease expense	1,200	1,500	$ 4,000
Operating lease payments	$ 2,400	$ 3,300
Weighted-average remaining lease term	0 years	2 years
Weighted-average discount rate	10.40%	11.00%
Minimum
Leases
Term of lease (in years)	1 year
Maximum
Leases
Term of lease (in years)	5 years
ASC 842
Leases
Term of lease (in years)				3 years
Lease liabilities	$ 1,900			$ 1,400	$ 4,700
Right-of-use assets	$ 1,900			$ 1,400	$ 3,800