Commitments and Contingencies - Lease Cost (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Lease, Cost [Abstract]
Amortization of right-of-use assets	$ 27,000	$ 45,000	$ 53,000	$ 99,000
Interest on lease obligations	0	1,000	0	1,000
Finance lease costs	27,000	46,000	53,000	100,000
Operating lease cost	1,033,000	1,032,000	2,065,000	2,100,000
Short-term lease cost	10,000	16,000	10,000	47,000
Sublease income	0	0	0	(55,000)
Total lease cost	1,070,000	1,094,000	2,128,000	2,192,000
Variable lease cost	$ 0	$ 0	$ 0	$ 0