Guarantor Subsidiaries (Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net cash (used in)/provided by operating activities - continuing operations	$ 265,116	$ 258,789
Net cash provided by operating activities - discontinued operations	(2,408)	9,684
Total cash (used in)/provided by operating activities	262,708	268,473
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of property and equipment	(51,956)	(38,753)
Purchases of capitalized data and other intangible assets	(28,795)	(24,054)
Cash paid for acquisitions, net of cash acquired	(70,904)	111
Purchases of investments	(2,351)	0
Proceeds from sale of property and equipment	0	1,852
Change in restricted cash	5,728	122
Net cash used in investing activities - continuing operations	(147,478)	(42,722)
Net cash used in investing activities - discontinued operations	2,152	(1,512)
Total cash used in investing activities	(145,326)	(44,234)
Cash Received From Sale Of Subsidiary	800	10,000
Net Cash Provided by (Used in) Financing Activities [Abstract]
Proceeds from long-term debt	1,075	0
Repayments of long-term debt	(4,516)	(114,365)
Share repurchased and retired	(133,565)	(226,629)
Proceeds from issuance of stock related to stock options and employee benefit plans	11,662	9,624
Minimum tax withholding paid on behalf of employees for restricted stock units	(6,893)	(3,015)
Tax benefit related to stock options	2,895	643
Net cash used in financing activities - continuing operations	(129,342)	(333,752)
Net cash provided by financing activities - discontinued operations	0	3
Total cash (used in)/provided by financing activities	(129,342)	(333,749)
Effect of exchange rate on cash	(1,341)	0
Net (decrease)/increase in cash and cash equivalents	(13,301)	(109,510)
Cash and cash equivalents at beginning of period	148,858	259,266
Less: Change in cash and cash equivalents - discontinued operations	(256)	8,175
Plus: Cash swept from discontinued operations	(256)	12,971
Cash and cash equivalents at end of period	135,557	154,552
Payments to Noncontrolling Interests	0	10
Proceeds from Sale, Maturity and Collection of Investments	0	8,000
Parent [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net cash (used in)/provided by operating activities - continuing operations	234	(15,160)
Net cash provided by operating activities - discontinued operations	0	0
Total cash (used in)/provided by operating activities	234	(15,160)
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of property and equipment	(6,333)	(1,407)
Purchases of capitalized data and other intangible assets	(362)	0
Cash paid for acquisitions, net of cash acquired	0	0
Purchases of investments	0
Proceeds from Divestiture of Businesses	0
Proceeds from sale of property and equipment		0
Change in restricted cash	3,678	0
Net cash used in investing activities - continuing operations	(3,017)	(1,407)
Net cash used in investing activities - discontinued operations	0	0
Total cash used in investing activities	(3,017)	(1,407)
Cash Received From Sale Of Subsidiary		0
Net Cash Provided by (Used in) Financing Activities [Abstract]
Proceeds from long-term debt	0
Repayments of long-term debt	(4,375)	(103,018)
Share repurchased and retired	(133,565)	(226,629)
Proceeds from issuance of stock related to stock options and employee benefit plans	11,662	9,624
Minimum tax withholding paid on behalf of employees for restricted stock units	(6,893)	(3,015)
Tax benefit related to stock options	2,895	643
Intercompany Payments	0	(6,949)
Other	128,451	233,946
Net cash used in financing activities - continuing operations	(1,825)	(95,398)
Net cash provided by financing activities - discontinued operations	0	0
Total cash (used in)/provided by financing activities	(1,825)	(95,398)
Effect of exchange rate on cash	0
Net (decrease)/increase in cash and cash equivalents	(4,608)	(111,965)
Cash and cash equivalents at beginning of period	111,305	229,871
Less: Change in cash and cash equivalents - discontinued operations	0	0
Plus: Cash swept from discontinued operations	(256)	12,133
Cash and cash equivalents at end of period	106,441	130,039
Payments to Noncontrolling Interests		0
Payments of Ordinary Dividends, Common Stock		0
Proceeds from Sale, Maturity and Collection of Investments		0
Guarantor Subsidiaries [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net cash (used in)/provided by operating activities - continuing operations	250,562	266,105
Net cash provided by operating activities - discontinued operations	(4,560)	9,684
Total cash (used in)/provided by operating activities	246,002	275,789
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of property and equipment	(39,903)	(27,942)
Purchases of capitalized data and other intangible assets	(24,725)	(21,537)
Cash paid for acquisitions, net of cash acquired	(71,446)	111
Purchases of investments	(2,351)
Proceeds from Divestiture of Businesses	800
Proceeds from sale of property and equipment		1,852
Change in restricted cash	0	(184)
Net cash used in investing activities - continuing operations	(137,625)	(29,700)
Net cash used in investing activities - discontinued operations	2,152	(2,350)
Total cash used in investing activities	(135,473)	(32,050)
Cash Received From Sale Of Subsidiary		10,000
Net Cash Provided by (Used in) Financing Activities [Abstract]
Proceeds from long-term debt	1,075
Repayments of long-term debt	(141)	(11,251)
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
Tax benefit related to stock options	0	0
Intercompany Payments	(113,531)	(233,946)
Other	0	0
Net cash used in financing activities - continuing operations	(112,597)	(245,197)
Net cash provided by financing activities - discontinued operations	0	3
Total cash (used in)/provided by financing activities	(112,597)	(245,194)
Effect of exchange rate on cash	0
Net (decrease)/increase in cash and cash equivalents	(2,068)	(1,455)
Cash and cash equivalents at beginning of period	1,812	9,106
Less: Change in cash and cash equivalents - discontinued operations	(2,408)	7,337
Plus: Cash swept from discontinued operations	(2,152)	0
Cash and cash equivalents at end of period	0	314
Payments to Noncontrolling Interests		0
Payments of Ordinary Dividends, Common Stock		0
Proceeds from Sale, Maturity and Collection of Investments		8,000
Non-Guarantor Subsidiaries [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net cash (used in)/provided by operating activities - continuing operations	14,320	7,844
Net cash provided by operating activities - discontinued operations	2,152	0
Total cash (used in)/provided by operating activities	16,472	7,844
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of property and equipment	(5,720)	(9,404)
Purchases of capitalized data and other intangible assets	(3,708)	(2,517)
Cash paid for acquisitions, net of cash acquired	542	0
Purchases of investments	0
Proceeds from Divestiture of Businesses	0
Proceeds from sale of property and equipment		0
Change in restricted cash	2,050	306
Net cash used in investing activities - continuing operations	(6,836)	(11,615)
Net cash used in investing activities - discontinued operations	0	838
Total cash used in investing activities	(6,836)	(10,777)
Cash Received From Sale Of Subsidiary		0
Net Cash Provided by (Used in) Financing Activities [Abstract]
Proceeds from long-term debt	0
Repayments of long-term debt	0	(96)
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
Tax benefit related to stock options	0	0
Intercompany Payments	(14,920)	0
Other	0	6,949
Net cash used in financing activities - continuing operations	(14,920)	6,843
Net cash provided by financing activities - discontinued operations	0	0
Total cash (used in)/provided by financing activities	(14,920)	6,843
Effect of exchange rate on cash	(1,341)
Net (decrease)/increase in cash and cash equivalents	(6,625)	3,910
Cash and cash equivalents at beginning of period	35,741	20,289
Less: Change in cash and cash equivalents - discontinued operations	2,152	838
Plus: Cash swept from discontinued operations	2,152	838
Cash and cash equivalents at end of period	29,116	24,199
Payments to Noncontrolling Interests		10
Payments of Ordinary Dividends, Common Stock		0
Proceeds from Sale, Maturity and Collection of Investments		0
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
Purchases of investments	0
Proceeds from Divestiture of Businesses	0
Proceeds from sale of property and equipment		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
Cash Received From Sale Of Subsidiary		0
Net Cash Provided by (Used in) Financing Activities [Abstract]
Proceeds from long-term debt	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
Tax benefit related to stock options	0	0
Intercompany Payments	128,451	240,895
Other	(128,451)	(240,895)
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
Effect of exchange rate on cash	0
Net (decrease)/increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Less: Change in cash and cash equivalents - discontinued operations	0	0
Plus: Cash swept from discontinued operations	0	0
Cash and cash equivalents at end of period	0	0
Payments to Noncontrolling Interests		0
Payments of Ordinary Dividends, Common Stock		0
Proceeds from Sale, Maturity and Collection of Investments		0
Total [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net cash (used in)/provided by operating activities - continuing operations	265,116	258,789
Net cash provided by operating activities - discontinued operations	(2,408)	9,684
Total cash (used in)/provided by operating activities	262,708	268,473
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of property and equipment	(51,956)	(38,753)
Purchases of capitalized data and other intangible assets	(28,795)	(24,054)
Cash paid for acquisitions, net of cash acquired	(70,904)	111
Purchases of investments	(2,351)
Proceeds from Divestiture of Businesses	800
Proceeds from sale of property and equipment		1,852
Change in restricted cash	5,728	122
Net cash used in investing activities - continuing operations	(147,478)	(42,722)
Net cash used in investing activities - discontinued operations	2,152	(1,512)
Total cash used in investing activities	(145,326)	(44,234)
Cash Received From Sale Of Subsidiary		10,000
Net Cash Provided by (Used in) Financing Activities [Abstract]
Repayments of long-term debt	(4,516)	(114,365)
Share repurchased and retired	(133,565)	(226,629)
Proceeds from issuance of stock related to stock options and employee benefit plans	11,662	9,624
Minimum tax withholding paid on behalf of employees for restricted stock units	(6,893)	(3,015)
Tax benefit related to stock options	2,895	643
Intercompany Payments	0	0
Other	0	0
Net cash used in financing activities - continuing operations	(129,342)	(333,752)
Net cash provided by financing activities - discontinued operations	0	3
Total cash (used in)/provided by financing activities	(129,342)	(333,749)
Effect of exchange rate on cash	(1,341)
Net (decrease)/increase in cash and cash equivalents	(13,301)	(109,510)
Cash and cash equivalents at beginning of period	148,858	259,266
Less: Change in cash and cash equivalents - discontinued operations	(256)	8,175
Plus: Cash swept from discontinued operations	(256)
Cash and cash equivalents at end of period	135,557	154,552
Payments to Noncontrolling Interests		10
Payments of Ordinary Dividends, Common Stock		0
Proceeds from Sale, Maturity and Collection of Investments		$ 8,000