Guarantor Subsidiaries (Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Feb. 06, 2012
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net cash (used in)/provided by operating activities - continuing operations	$ 93,071	$ 69,726
Net cash provided by operating activities - discontinued operations	(543)	(4,694)
Total cash (used in)/provided by operating activities	92,528	65,032
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of property and equipment	(18,150)	(13,519)
Purchases of capitalized data and other intangible assets	(9,489)	(6,959)
Cash paid for acquisitions, net of cash acquired	(7,027)
Cash Received From Sale Of Subsidiary	800	0
Purchases of investments	(2,351)	0
Proceeds from sale of property and equipment	0	45
Change in restricted cash	(40)	(186)
Net cash used in investing activities - continuing operations	(36,257)	(20,619)
Net cash used in investing activities - discontinued operations	0	239
Total cash used in investing activities	(36,257)	(20,380)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Repayments of long-term debt	(4,400)	(52,247)
Share repurchased and retired	(75,676)	0
Proceeds from issuance of stock related to stock options and employee benefit plans	4,621	187
Minimum tax withholding paid on behalf of employees for restricted stock units	(6,436)	0
Distribution to noncontrolling interests	0	(10)
Tax benefit related to stock options	2,321	56
Net cash used in financing activities - continuing operations	(79,570)	(52,014)
Net cash provided by financing activities - discontinued operations	0	1
Total cash (used in)/provided by financing activities	(79,570)	(52,013)
Net (decrease)/increase in cash and cash equivalents	(23,299)	(7,361)
Cash and cash equivalents at beginning of period		259,266
Less: Change in cash and cash equivalents - discontinued operations	(543)	(4,454)
Plus: Cash swept from discontinued operations	(543)	0
Cash and cash equivalents at end of period	125,559	256,359
Parent [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net cash (used in)/provided by operating activities - continuing operations	25,818	19,166
Net cash provided by operating activities - discontinued operations	0	0
Total cash (used in)/provided by operating activities	25,818	19,166
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of property and equipment	(871)	(989)
Purchases of capitalized data and other intangible assets	(390)	0
Cash paid for acquisitions, net of cash acquired	0	0
Proceeds from sale of subsidiary and other decreases in noncontrolling interest, net		0
Purchases of investments	0	0
Proceeds from Divestiture of Businesses	0
Proceeds from sale of property and equipment		0
Proceeds from sale of investments		0
Change in restricted cash	(4)	0
Net cash used in investing activities - continuing operations	(1,265)	(989)
Net cash used in investing activities - discontinued operations	0	0
Total cash used in investing activities	(1,265)	(989)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Purchases of redeemable noncontrolling interests		0
Proceeds from long-term debt		0
Debt issuance costs		0
Repayments of long-term debt	(4,375)	(42,000)
Share repurchased and retired	(75,676)	0
Proceeds from issuance of stock related to stock options and employee benefit plans	4,621	187
Minimum tax withholding paid on behalf of employees for restricted stock units	(6,436)	0
Distribution to noncontrolling interests	0	0
Tax benefit related to stock options	2,326	56
Intercompany Payments	0	(9,065)
Other	39,621	45,236
Net cash used in financing activities - continuing operations	(39,919)	(5,586)
Net cash provided by financing activities - discontinued operations	0	0
Total cash (used in)/provided by financing activities	(39,919)	(5,586)
Net (decrease)/increase in cash and cash equivalents	(15,366)	12,591
Cash and cash equivalents at beginning of period	111,305	229,871	242,462
Less: Change in cash and cash equivalents - discontinued operations	0	0
Plus: Cash swept from discontinued operations	(543)
Cash and cash equivalents at end of period	95,396		242,462
Guarantor Subsidiaries [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net cash (used in)/provided by operating activities - continuing operations	71,132	58,236
Net cash provided by operating activities - discontinued operations	(543)	(4,694)
Total cash (used in)/provided by operating activities	70,589	53,542
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of property and equipment	(15,334)	(8,762)
Purchases of capitalized data and other intangible assets	(7,820)	(6,876)
Cash paid for acquisitions, net of cash acquired	(7,027)	0
Proceeds from sale of subsidiary and other decreases in noncontrolling interest, net		0
Purchases of investments	(2,351)	0
Proceeds from Divestiture of Businesses	800
Proceeds from sale of property and equipment		45
Proceeds from sale of investments		0
Change in restricted cash	1	(186)
Net cash used in investing activities - continuing operations	(31,731)	(15,779)
Net cash used in investing activities - discontinued operations	0	239
Total cash used in investing activities	(31,731)	(15,540)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Purchases of redeemable noncontrolling interests		0
Proceeds from long-term debt		0
Debt issuance costs		0
Repayments of long-term debt	(25)	(10,214)
Share repurchased and retired	0	0
Proceeds from issuance of stock related to stock options and employee benefit plans	0	0
Minimum tax withholding paid on behalf of employees for restricted stock units	0	0
Distribution to noncontrolling interests	0	0
Tax benefit related to stock options	(5)	0
Intercompany Payments	(31,601)	(45,236)
Other	0	0
Net cash used in financing activities - continuing operations	(31,631)	(55,450)
Net cash provided by financing activities - discontinued operations	0	1
Total cash (used in)/provided by financing activities	(31,631)	(55,449)
Net (decrease)/increase in cash and cash equivalents	7,227	(17,447)
Cash and cash equivalents at beginning of period	1,812	9,106	(3,887)
Less: Change in cash and cash equivalents - discontinued operations	(543)	(4,454)
Plus: Cash swept from discontinued operations	0
Cash and cash equivalents at end of period	9,582		(3,887)
Non-Guarantor Subsidiaries [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net cash (used in)/provided by operating activities - continuing operations	(3,879)	(7,676)
Net cash provided by operating activities - discontinued operations	0	0
Total cash (used in)/provided by operating activities	(3,879)	(7,676)
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of property and equipment	(1,945)	(3,768)
Purchases of capitalized data and other intangible assets	(1,279)	(83)
Cash paid for acquisitions, net of cash acquired	0	0
Proceeds from sale of subsidiary and other decreases in noncontrolling interest, net		0
Purchases of investments	0	0
Proceeds from Divestiture of Businesses	0
Proceeds from sale of property and equipment		0
Proceeds from sale of investments		0
Change in restricted cash	(37)	0
Net cash used in investing activities - continuing operations	(3,261)	(3,851)
Net cash used in investing activities - discontinued operations	0	0
Total cash used in investing activities	(3,261)	(3,851)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Purchases of redeemable noncontrolling interests		0
Proceeds from long-term debt		0
Debt issuance costs		0
Repayments of long-term debt	0	(33)
Share repurchased and retired	0	0
Proceeds from issuance of stock related to stock options and employee benefit plans	0	0
Minimum tax withholding paid on behalf of employees for restricted stock units	0	0
Distribution to noncontrolling interests	0	(10)
Tax benefit related to stock options	0	0
Intercompany Payments	(8,020)	0
Other	0	9,065
Net cash used in financing activities - continuing operations	(8,020)	9,022
Net cash provided by financing activities - discontinued operations	0	0
Total cash (used in)/provided by financing activities	(8,020)	9,022
Net (decrease)/increase in cash and cash equivalents	(15,160)	(2,505)
Cash and cash equivalents at beginning of period	35,741	20,289	17,784
Less: Change in cash and cash equivalents - discontinued operations	0	0
Plus: Cash swept from discontinued operations	0
Cash and cash equivalents at end of period	20,581		17,784
Consolidation, Eliminations [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net cash (used in)/provided by operating activities - continuing operations	0	0
Net cash provided by operating activities - discontinued operations	0	0
Total cash (used in)/provided by operating activities	0	0
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of property and equipment	0	0
Purchases of capitalized data and other intangible assets	0	0
Cash paid for acquisitions, net of cash acquired	0	0
Proceeds from sale of subsidiary and other decreases in noncontrolling interest, net		0
Purchases of investments	0	0
Proceeds from Divestiture of Businesses	0
Proceeds from sale of property and equipment		0
Proceeds from sale of investments		0
Change in restricted cash	0	0
Net cash used in investing activities - continuing operations	0	0
Net cash used in investing activities - discontinued operations	0	0
Total cash used in investing activities	0	0
Net Cash Provided by (Used in) Financing Activities [Abstract]
Purchases of redeemable noncontrolling interests		0
Proceeds from long-term debt		0
Debt issuance costs		0
Repayments of long-term debt	0	0
Share repurchased and retired	0	0
Proceeds from issuance of stock related to stock options and employee benefit plans	0	0
Minimum tax withholding paid on behalf of employees for restricted stock units	0	0
Distribution to noncontrolling interests	0	0
Tax benefit related to stock options	0	0
Intercompany Payments	39,621	54,301
Other	(39,621)	(54,301)
Net cash used in financing activities - continuing operations	0	0
Net cash provided by financing activities - discontinued operations	0	0
Total cash (used in)/provided by financing activities	0	0
Net (decrease)/increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0	0
Less: Change in cash and cash equivalents - discontinued operations	0	0
Plus: Cash swept from discontinued operations	0
Cash and cash equivalents at end of period	0		0
Total [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net cash (used in)/provided by operating activities - continuing operations	93,071	69,726
Net cash provided by operating activities - discontinued operations	(543)	(4,694)
Total cash (used in)/provided by operating activities	92,528	65,032
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of property and equipment	(18,150)	(13,519)
Purchases of capitalized data and other intangible assets	(9,489)	(6,959)
Cash paid for acquisitions, net of cash acquired	(7,027)	0
Proceeds from sale of subsidiary and other decreases in noncontrolling interest, net		0
Purchases of investments	(2,351)	0
Proceeds from Divestiture of Businesses	800
Proceeds from sale of property and equipment		45
Proceeds from sale of investments		0
Change in restricted cash	(40)	(186)
Net cash used in investing activities - continuing operations	(36,257)	(20,619)
Net cash used in investing activities - discontinued operations	0	239
Total cash used in investing activities	(36,257)	(20,380)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Purchases of redeemable noncontrolling interests		0
Proceeds from long-term debt		0
Debt issuance costs		0
Repayments of long-term debt	(4,400)	(52,247)
Share repurchased and retired	(75,676)	0
Proceeds from issuance of stock related to stock options and employee benefit plans	4,621	187
Minimum tax withholding paid on behalf of employees for restricted stock units	(6,436)	0
Distribution to noncontrolling interests	0	(10)
Tax benefit related to stock options	2,321	56
Intercompany Payments	0	0
Other	0	0
Net cash used in financing activities - continuing operations	(79,570)	(52,014)
Net cash provided by financing activities - discontinued operations	0	1
Total cash (used in)/provided by financing activities	(79,570)	(52,013)
Net (decrease)/increase in cash and cash equivalents	(23,299)	(7,361)
Cash and cash equivalents at beginning of period	148,858	259,266	256,359
Less: Change in cash and cash equivalents - discontinued operations	(543)	(4,454)
Plus: Cash swept from discontinued operations	(543)
Cash and cash equivalents at end of period	$ 125,559		$ 256,359