Significant Accounting Policies - Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Significant Accounting Policies Line Items [Line Items]
Gross Carrying Amount	$ 263,335	$ 247,375
Accumulated Amortization / Depreciation	(192,354)	(172,289)
Net Carrying Amount	70,981	75,086
Internal-use software
Significant Accounting Policies Line Items [Line Items]
Gross Carrying Amount	155,984	145,248
Accumulated Amortization / Depreciation	(100,734)	(91,542)
Net Carrying Amount	55,250	53,706
Leasehold improvements
Significant Accounting Policies Line Items [Line Items]
Gross Carrying Amount	39,134	34,805
Accumulated Amortization / Depreciation	(26,236)	(18,108)
Net Carrying Amount	12,898	16,697
Furniture and equipment
Significant Accounting Policies Line Items [Line Items]
Gross Carrying Amount	68,217	67,322
Accumulated Amortization / Depreciation	(65,384)	(62,639)
Net Carrying Amount	$ 2,833	$ 4,683