Capitalized Data and Database Development Costs, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Capitalized Costs and Database Development [Line Items]
Capitalized data and database costs, net	$ 636,948	$ 601,025
Less accumulated amortization	(307,545)	(273,104)
Capitalized data and database cost, net	329,403	327,921
Amortization expense	35,800	34,600	$ 33,200
Property data [Member]
Capitalized Costs and Database Development [Line Items]
Capitalized data and database costs, net	564,515	528,527
Flood data [Member]
Capitalized Costs and Database Development [Line Items]
Capitalized data and database costs, net	55,416	55,416
Eviction data [Member]
Capitalized Costs and Database Development [Line Items]
Capitalized data and database costs, net	$ 17,017	$ 17,082