Commitments and Contingencies - Lease Cost (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Schedule of Commitments and Contingencies [Line Items]
Amortization of right-of-use assets	$ 26,000	$ 27,000	$ 79,000	$ 126,000
Interest on lease obligations	0	0	0	1,000
Finance lease costs	26,000	27,000	79,000	127,000
Operating lease cost	1,032,000	1,033,000	3,097,000	3,133,000
Short-term lease costs	30,000	0	40,000	47,000
Sublease income	0	0	0	(55,000)
Total lease cost	1,088,000	1,060,000	3,216,000	3,252,000
Variable lease cost	$ 0	$ 0	$ 0	$ 0
Minimum
Schedule of Commitments and Contingencies [Line Items]
Short-term lease, term			1 month
Maximum
Schedule of Commitments and Contingencies [Line Items]
Short-term lease, term			1 year