Property and Equipment - Property and Equipment Schedule (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment	$ 334,793	$ 288,952
Less accumulated depreciation and amortization	(189,317)	(168,683)
Property and equipment, net	145,476	120,269
Land
Property, Plant and Equipment [Line Items]
Property and equipment	205	205
Building
Property, Plant and Equipment [Line Items]
Property and equipment	605	1,105
Computer equipment, furniture, and office equipment
Property, Plant and Equipment [Line Items]
Property and equipment	61,193	60,110
Computer software purchased
Property, Plant and Equipment [Line Items]
Property and equipment	31,218	27,276
Capitalized internal-use software
Property, Plant and Equipment [Line Items]
Property and equipment	227,137	187,723
Tenant improvements
Property, Plant and Equipment [Line Items]
Property and equipment	$ 14,435	$ 12,533