Guarantor Subsidiaries Balance Sheet (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Current assets	$ 655,979	$ 1,052,301
Property and equipment, net	214,237	197,426
Goodwill	1,472,206	1,289,888	1,276,932
Other identifiable intangible assets, net	164,365	109,850
Capitalized data and database costs, net	304,006	211,331
Investments in affiliates	113,809	165,709
Deferred income tax assets, long-term	38,305	6,344
Restricted cash	22,044	21,095
Other assets	125,120	180,881
Total assets	3,110,071	3,234,825
Current liabilities	500,659	744,438
Long-term debt, net	846,027	487,437
Deferred revenue	338,799	350,827
Deferred income tax, long term	18,383	0
Other liabilities	161,382	106,982
Total equity	1,244,821	1,545,141	3,156,673	3,375,659
Total liabilities and equity	3,110,071	3,234,825
Parent Company [Member]
Current assets	284,329	421,614
Property and equipment, net	8,500	11,417
Goodwill	0	0
Other identifiable intangible assets, net	0	0
Capitalized data and database costs, net	0	0
Investments in affiliates	0	18,383
Deferred income tax assets, long-term	53,724	34,799
Restricted cash	18,298	20,973
Investments in subsidiaries	1,799,365	1,773,507
Other assets	92,910	118,775
Total assets	2,257,126	2,399,468
Current liabilities	95,237	326,258
Long-term debt, net	784,570	443,838
Deferred revenue	0	0
Deferred income tax, long term	0	0
Other liabilities	132,498	84,231
Total equity	1,244,821	1,545,141
Total liabilities and equity	2,257,126	2,399,468
Guarantor Subsidiaries [Member]
Current assets	339,098	567,682
Property and equipment, net	175,129	180,679
Goodwill	1,288,328	1,270,751
Other identifiable intangible assets, net	107,994	106,060
Capitalized data and database costs, net	218,534	211,325
Investments in affiliates	108,323	147,326
Deferred income tax assets, long-term	(15,419)	(28,769)
Restricted cash	122	122
Investments in subsidiaries	0	0
Other assets	30,151	60,000
Total assets	2,252,260	2,515,176
Current liabilities	369,631	408,611
Long-term debt, net	10,412	43,599
Deferred revenue	338,799	350,827
Deferred income tax, long term	0	0
Other liabilities	24,333	22,698
Total equity	1,509,085	1,689,441
Total liabilities and equity	2,252,260	2,515,176
Non-Guarantor Subsidiaries [Member]
Current assets	32,552	63,005
Property and equipment, net	30,608	5,330
Goodwill	183,878	19,137
Other identifiable intangible assets, net	56,371	3,790
Capitalized data and database costs, net	85,472	6
Investments in affiliates	5,486	0
Deferred income tax assets, long-term	0	314
Restricted cash	3,624	0
Investments in subsidiaries	0	0
Other assets	2,059	2,106
Total assets	400,050	93,688
Current liabilities	35,791	9,569
Long-term debt, net	51,045	0
Deferred revenue	0	0
Deferred income tax, long term	18,383	0
Other liabilities	4,551	53
Total equity	290,280	84,066
Total liabilities and equity	400,050	93,688
Consolidation, Eliminations [Member]
Current assets	0	0
Property and equipment, net	0	0
Goodwill	0	0
Other identifiable intangible assets, net		0
Capitalized data and database costs, net	0	0
Investments in affiliates	0	0
Deferred income tax assets, long-term	0	0
Restricted cash	0	0
Investments in subsidiaries	(1,799,365)	(1,773,507)
Other assets	0	0
Total assets	(1,799,365)	(1,773,507)
Current liabilities	0	0
Long-term debt, net	0	0
Deferred revenue	0	0
Deferred income tax, long term	0	0
Other liabilities	0	0
Total equity	(1,799,365)	(1,773,507)
Total liabilities and equity	(1,799,365)	(1,773,507)
Total [Member]
Current assets	655,979	1,052,301
Property and equipment, net	214,237	197,426
Goodwill	1,472,206	1,289,888
Other identifiable intangible assets, net	164,365	109,850
Capitalized data and database costs, net	304,006	211,331
Investments in affiliates	113,809	165,709
Deferred income tax assets, long-term	38,305	6,344
Restricted cash	22,044	21,095
Investments in subsidiaries	0	0
Other assets	125,120	180,881
Total assets	3,110,071	3,234,825
Current liabilities	500,659	744,438
Long-term debt, net	846,027	487,437
Deferred revenue	338,799	350,827
Deferred income tax, long term	18,383	0
Other liabilities	161,382	106,982
Total equity	1,244,821	1,545,141
Total liabilities and equity	$ 3,110,071	$ 3,234,825