Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ (65,236)	$ (59,766)
Property and equipment, net	60,836	58,671
Property and equipment, gross
Property, Plant and Equipment [Line Items]
Property and equipment, gross	112,034	108,072
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	33,480	33,455
Website and software development costs
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 52,818	50,439
Website and software development costs | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives (Years)	2 years
Website and software development costs | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives (Years)	3 years
Computer and office equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 15,763	14,216
Computer and office equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives (Years)	3 years
Computer and office equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives (Years)	5 years
Software
Property, Plant and Equipment [Line Items]
Useful Lives (Years)	3 years
Property and equipment, gross	$ 1,871	1,871
Furniture
Property, Plant and Equipment [Line Items]
Useful Lives (Years)	7 years
Property and equipment, gross	$ 8,102	8,091
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 14,038	$ 10,365