Segment Reporting (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Operating segment revenue by type of service
Revenues	$ 346,501	[1]	$ 312,869	[1]
Risk Assessment [Member]
Operating segment revenue by type of service
Revenues	144,969		140,543
Risk Assessment [Member] | Industry Standard Insurance Programs [Member]
Operating segment revenue by type of service
Revenues	99,134		92,857
Risk Assessment [Member] | Property Specific Rating And Underwriting Information [Member]
Operating segment revenue by type of service
Revenues	32,557		34,497
Risk Assessment [Member] | Statistical Agency And Data Services [Member]
Operating segment revenue by type of service
Revenues	7,724		7,742
Risk Assessment [Member] | Actuarial Services [Member]
Operating segment revenue by type of service
Revenues	5,554		5,447
Decision Analytics [Member]
Operating segment revenue by type of service
Revenues	201,532		172,326
Decision Analytics [Member] | Insurance [Member]
Operating segment revenue by type of service
Revenues	116,336		105,300
Decision Analytics [Member] | Mortgage and financial services [Member]
Operating segment revenue by type of service
Revenues	34,275		32,696
Decision Analytics [Member] | Healthcare [Member]
Operating segment revenue by type of service
Revenues	30,448		15,617
Decision Analytics [Member] | Specialized markets [Member]
Operating segment revenue by type of service
Revenues	$ 20,473		$ 18,713

[1] See Note 13. Related Parties for further information.