Nature of Business and Summary of Significant Accounting Policies - Summary of Property and Equipment Estimated Useful Lives and Balances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 206,606	$ 190,121
Less: accumulated depreciation	(136,226)	(117,392)
Property and equipment, net	70,380	72,729
Computer and office equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 143,942	129,359
Computer and office equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives	3 years
Computer and office equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 33,346	32,096
Useful Lives, description	Lesser of useful life of improvement or remaining life of lease
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 12,980	12,500
Useful Lives	7 years
Building and improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 14,553	14,381
Building and improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives	7 years
Building and improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives	30 years
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,785	$ 1,785
Useful Lives, description	Non-depreciable