Fixed Assets (Details) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization	$ 75,993,000	$ 73,693,000	$ 75,993,000	$ 73,693,000
Less: Accumulated depreciation and amortization	(50,017,000)	(40,670,000)	(50,017,000)	(40,670,000)
Fixed assets, net	25,976,000	33,023,000	25,976,000	33,023,000
Depreciation, Amortization and Accretion, Net			11,000,000	9,600,000	$ 7,300,000
Finance Lease, Right-of-Use Asset, before Accumulated Amortization	6,468,000	6,172,000	6,468,000	6,172,000
Finance Lease, Right-of-Use Asset, Amortization			1,274,000	1,232,000	$ 1,266,000
Finance Lease, Right-of-Use Asset, Accumulated Amortization	4,700,000	3,400,000	4,700,000	3,400,000
Telecommunication and computer equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	9,379,000	7,921,000	9,379,000	7,921,000
Computer software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	13,715,000	11,813,000	13,715,000	11,813,000
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3,607,000	3,387,000	3,607,000	3,387,000
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	42,749,000	40,468,000	42,749,000	40,468,000
Airplane and related equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	0	3,932,000	0	3,932,000
Payments to Acquire Productive Assets		4,500,000
Gain (Loss) on Disposition of Other Assets	300,000
Other Noncurrent Assets
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 75,000	$ 0	$ 75,000	$ 0