Guarantor Subsidiaries (Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net cash (used in)/provided by operating activities - continuing operations		$ 302,413	$ 319,945	$ 143,743
Net cash provided by operating activities - discontinued operations		51,408	43,200	19,253
Total cash (used in)/provided by operating activities		353,821	363,145	162,996
Cash flows from investing activities:
Purchases of property and equipment		(68,740)	(48,266)	(41,153)
Purchases of capitalized data and other intangible assets		(37,841)	(32,189)	(27,009)
Cash paid for acquisitions, net of cash acquired		(92,049)	(78,354)	(214,215)
Cash received from sale of subsidiary, net		2,263	10,000	28,054
Purchases of investments		(2,351)	0	(26,398)
Proceeds from sale of property and equipment		0	1,863	25,042
Proceeds from sale of investments		0	8,000	74,621
Change in restricted cash		10,068	86	2,091
Net cash used in investing activities - continuing operations		(188,650)	(138,860)	(178,967)
Net cash provided by/(used in) investing activities - discontinued operations		1,857	(8,482)	(8,706)
Total cash used in by investing activities		(186,793)	(147,342)	(187,673)
Cash flows from financing activities:
Purchases of redeemable noncontrolling interests		0	0	(72,000)
Proceeds from long-term debt		51,647	50,000	858,154
Debt issuance costs		(10,436)	0	(22,810)
Repayments of long-term debt		(4,666)	(166,715)	(733,407)
Shares repurchased and retired		(241,161)	(226,629)	(176,512)
Proceeds from issuance of stock related to stock options and employee benefit plans		28,232	13,497	3,087
Minimum tax withholding paid on behalf of employees for restricted stock units		(8,665)	(3,466)	(2,023)
Distribution to noncontrolling interests		0	(10)	(4,835)
Tax benefit related to stock options		5,146	935	344
Intercompany loan payments		0	0	0
Intercompany loan proceeds		0	0	0
Net cash provided by/(used in) financing activities - continuing operations		(179,903)	(332,388)	(150,002)
Net cash used in financing activities - discontinued operations		0	(79)	64
Total cash provided by/(used in) financing activities		(179,903)	(332,467)	(149,938)
Effect of Exchange Rate on cash		(2,116)	(153)	65
Net decrease in cash and cash equivalents		(14,991)	(116,817)	(174,550)
Cash and cash equivalents at beginning of year		151,986	260,029	419,701
Less: Change in cash and cash equivalents of discontinued operations	34,639	53,265	34,639	10,611
Plus: Cash swept from discontinued operations	43,413	51,011	43,413	25,489
Cash and cash equivalents at end of year	151,986	134,741	151,986	260,029
Parent [Member]
Cash flows from operating activities:
Net cash (used in)/provided by operating activities - continuing operations		(52,150)	(60,340)	(11,053)
Net cash provided by operating activities - discontinued operations		0	0	(19)
Total cash (used in)/provided by operating activities		(52,150)	(60,340)	(11,072)
Cash flows from investing activities:
Purchases of property and equipment		(8,870)	(3,195)	(785)
Purchases of capitalized data and other intangible assets		(348)	0	0
Cash paid for acquisitions, net of cash acquired		0	0	(219,317)
Cash received from sale of subsidiary, net		0	0	0
Purchases of investments		0		(725)
Proceeds from sale of property and equipment			0	0
Proceeds from sale of investments			0	0
Change in restricted cash		7,964	(1)	2,674
Net cash used in investing activities - continuing operations		(1,254)	(3,196)	(218,153)
Net cash provided by/(used in) investing activities - discontinued operations		0	0	0
Total cash used in by investing activities		(1,254)	(3,196)	(218,153)
Cash flows from financing activities:
Purchases of redeemable noncontrolling interests				0
Proceeds from long-term debt		50,000	50,000	750,000
Debt issuance costs		0		(22,810)
Repayments of long-term debt		(4,375)	(103,368)	(575,787)
Shares repurchased and retired		(241,161)	(226,629)	(176,512)
Proceeds from issuance of stock related to stock options and employee benefit plans		28,232	13,497	3,087
Minimum tax withholding paid on behalf of employees for restricted stock units		(8,665)	(3,466)	(2,023)
Distribution to noncontrolling interests			0	0
Tax benefit related to stock options		5,146	935	344
Intercompany loan payments		0	(66,765)	0
Intercompany loan proceeds		218,456	278,231	131,831
Net cash provided by/(used in) financing activities - continuing operations		47,633	(57,565)	108,130
Net cash used in financing activities - discontinued operations		0	0	0
Total cash provided by/(used in) financing activities		47,633	(57,565)	108,130
Effect of Exchange Rate on cash		0	0	0
Net decrease in cash and cash equivalents		(5,771)	(121,101)	(121,095)
Cash and cash equivalents at beginning of year		111,305	229,871	355,974
Less: Change in cash and cash equivalents of discontinued operations	0	0		(19)
Plus: Cash swept from discontinued operations	2,535	(902)		(5,027)
Cash and cash equivalents at end of year	111,305	104,632	111,305	229,871
Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash (used in)/provided by operating activities - continuing operations		328,483	363,358	151,801
Net cash provided by operating activities - discontinued operations		49,902	43,200	19,272
Total cash (used in)/provided by operating activities		378,385	406,558	171,073
Cash flows from investing activities:
Purchases of property and equipment		(51,655)	(33,618)	(34,862)
Purchases of capitalized data and other intangible assets		(23,171)	(28,792)	(26,447)
Cash paid for acquisitions, net of cash acquired		(92,591)	(78,354)	4,220
Cash received from sale of subsidiary, net		2,263	10,000	5,300
Purchases of investments		(2,351)		(25,673)
Proceeds from sale of property and equipment			1,863	25,042
Proceeds from sale of investments			8,000	74,621
Change in restricted cash		0	(184)	(1)
Net cash used in investing activities - continuing operations		(167,505)	(121,085)	22,200
Net cash provided by/(used in) investing activities - discontinued operations		1,857	(8,482)	(8,706)
Total cash used in by investing activities		(165,648)	(129,567)	13,494
Cash flows from financing activities:
Purchases of redeemable noncontrolling interests				(72,000)
Proceeds from long-term debt		1,647	0	54,544
Debt issuance costs		(10,436)		0
Repayments of long-term debt		(291)	(11,020)	(107,109)
Shares repurchased and retired		0	0	0
Proceeds from issuance of stock related to stock options and employee benefit plans		0	0	0
Minimum tax withholding paid on behalf of employees for restricted stock units		0	0	0
Distribution to noncontrolling interests			0	(4,290)
Tax benefit related to stock options		0	0	0
Intercompany loan payments		(208,194)	(278,231)	(78,584)
Intercompany loan proceeds		0	0	0
Net cash provided by/(used in) financing activities - continuing operations		(217,274)	(289,251)	(207,439)
Net cash used in financing activities - discontinued operations		0	(79)	64
Total cash provided by/(used in) financing activities		(217,274)	(289,330)	(207,375)
Effect of Exchange Rate on cash		0	0	0
Net decrease in cash and cash equivalents		(4,537)	(12,339)	(22,808)
Cash and cash equivalents at beginning of year		5,889	11,989	18,178
Less: Change in cash and cash equivalents of discontinued operations	34,639	51,759		10,630
Plus: Cash swept from discontinued operations	40,878	50,407		27,249
Cash and cash equivalents at end of year	5,889	0	5,889	11,989
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash (used in)/provided by operating activities - continuing operations		26,080	16,927	2,995
Net cash provided by operating activities - discontinued operations		1,506	0	0
Total cash (used in)/provided by operating activities		27,586	16,927	2,995
Cash flows from investing activities:
Purchases of property and equipment		(8,215)	(11,453)	(5,506)
Purchases of capitalized data and other intangible assets		(14,322)	(3,397)	(562)
Cash paid for acquisitions, net of cash acquired		542	0	882
Cash received from sale of subsidiary, net		0	0	22,754
Purchases of investments		0		0
Proceeds from sale of property and equipment			0	0
Proceeds from sale of investments			0	0
Change in restricted cash		2,104	271	(582)
Net cash used in investing activities - continuing operations		(19,891)	(14,579)	16,986
Net cash provided by/(used in) investing activities - discontinued operations		0	0	0
Total cash used in by investing activities		(19,891)	(14,579)	16,986
Cash flows from financing activities:
Purchases of redeemable noncontrolling interests				0
Proceeds from long-term debt		0	0	53,610
Debt issuance costs		0		0
Repayments of long-term debt		0	(52,327)	(50,511)
Shares repurchased and retired		0	0	0
Proceeds from issuance of stock related to stock options and employee benefit plans		0	0	0
Minimum tax withholding paid on behalf of employees for restricted stock units		0	0	0
Distribution to noncontrolling interests			(10)	(545)
Tax benefit related to stock options		0	0	0
Intercompany loan payments		(10,262)	0	(53,247)
Intercompany loan proceeds		0	66,765	0
Net cash provided by/(used in) financing activities - continuing operations		(10,262)	14,428	(50,693)
Net cash used in financing activities - discontinued operations		0	0	0
Total cash provided by/(used in) financing activities		(10,262)	14,428	(50,693)
Effect of Exchange Rate on cash		(2,116)	(153)	65
Net decrease in cash and cash equivalents		(4,683)	16,623	(30,647)
Cash and cash equivalents at beginning of year		34,792	18,169	45,549
Less: Change in cash and cash equivalents of discontinued operations	0	1,506		0
Plus: Cash swept from discontinued operations	0	1,506		3,267
Cash and cash equivalents at end of year	34,792	30,109	34,792	18,169
Consolidating/Eliminating Adjustments [Member]
Cash flows from operating activities:
Net cash (used in)/provided by operating activities - continuing operations		0	0	0
Net cash provided by operating activities - discontinued operations		0	0	0
Total cash (used in)/provided by operating activities		0	0	0
Cash flows from investing activities:
Purchases of property and equipment		0	0	0
Purchases of capitalized data and other intangible assets		0	0	0
Cash paid for acquisitions, net of cash acquired		0	0	0
Cash received from sale of subsidiary, net		0	0	0
Purchases of investments		0		0
Proceeds from sale of property and equipment			0	0
Proceeds from sale of investments			0	0
Change in restricted cash		0	0	0
Net cash used in investing activities - continuing operations		0	0	0
Net cash provided by/(used in) investing activities - discontinued operations		0	0	0
Total cash used in by investing activities		0	0	0
Cash flows from financing activities:
Purchases of redeemable noncontrolling interests				0
Proceeds from long-term debt		0	0	0
Debt issuance costs		0		0
Repayments of long-term debt		0	0	0
Shares repurchased and retired		0	0	0
Proceeds from issuance of stock related to stock options and employee benefit plans		0	0	0
Minimum tax withholding paid on behalf of employees for restricted stock units		0	0	0
Distribution to noncontrolling interests			0	0
Tax benefit related to stock options		0	0	0
Intercompany loan payments		218,456	344,996	131,831
Intercompany loan proceeds		(218,456)	(344,996)	(131,831)
Net cash provided by/(used in) financing activities - continuing operations		0	0	0
Net cash used in financing activities - discontinued operations		0	0	0
Total cash provided by/(used in) financing activities		0	0	0
Effect of Exchange Rate on cash		0	0	0
Net decrease in cash and cash equivalents		0	0	0
Cash and cash equivalents at beginning of year		0	0	0
Less: Change in cash and cash equivalents of discontinued operations	0	0		0
Plus: Cash swept from discontinued operations	0	0		0
Cash and cash equivalents at end of year	$ 0	$ 0	$ 0	$ 0