Guarantor Subsidiaries (Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net cash (used in)/provided by operating activities - continuing operations	$ 336,149	$ 335,593	$ 328,220
Net cash (used in)/provided by operating activities - discontinued operations	(7,612)	(13,717)	25,600
Total cash (used in)/provided by operating activities	328,537	321,876	353,820
Cash flows from investing activities:
Purchases of property and equipment	(44,149)	(52,025)	(68,745)
Purchases of capitalized data and other intangible assets	(36,409)	(35,129)	(37,841)
Cash paid for acquisitions, net of cash acquired	(194,491)	(694,871)	(92,049)
Cash received from sale of discontinued operations	0	25,366	2,263
Purchases of investments	(3,748)	0	(2,351)
Proceeds from sale of property and equipment	137	13,937	0
Change in restricted cash	1,434	(310)	10,068
Net cash used in investing activities - continuing operations	(277,226)	(743,032)	(188,655)
Net cash provided by investing activities - discontinued operations	0	1,536	1,862
Total cash used in by investing activities	(277,226)	(741,496)	(186,793)
Cash flows from financing activities:
Proceeds from long-term debt	114,375	690,017	51,647
Debt issuance costs	(6,452)	(14,042)	(10,436)
Repayments of long-term debt	(82,891)	(200,006)	(4,666)
Shares repurchased and retired	(97,430)	(91,475)	(241,161)
Proceeds from issuance of shares in connection with share-based compensation	22,569	15,213	28,232
Minimum tax withholding related to net share settlements	(15,230)	(15,980)	(8,665)
Tax benefit related to stock options	6,513	6,791	5,146
Intercompany payments	0	0	0
Intercompany proceeds	0	0	0
Net cash provided by/(used in) financing activities - continuing operations	(58,546)	390,518	(179,903)
Net cash provided by financing activities - discontinued operations	0	0	0
Total cash provided by/(used in) financing activities	(58,546)	390,518	(179,903)
Effect of Exchange Rate on cash	2,182	(625)	(2,116)
Net change in cash and cash equivalents	(5,053)	(29,727)	(14,992)
Cash and cash equivalents at beginning of year	104,677	134,419	149,568
Less: Change in cash and cash equivalents of discontinued operations	(7,612)	(12,181)	27,462
Plus: Cash swept (to)/from discontinued operations	(8,146)	(12,196)	27,305
Cash and cash equivalents at end of year	99,090	104,677	134,419
Parent [Member]
Cash flows from operating activities:
Net cash (used in)/provided by operating activities - continuing operations	(94,034)	9,433	(51,864)
Net cash (used in)/provided by operating activities - discontinued operations	0	0	0
Total cash (used in)/provided by operating activities	(94,034)	9,433	(51,864)
Cash flows from investing activities:
Purchases of property and equipment	(3,911)	(1,964)	(8,870)
Purchases of capitalized data and other intangible assets	0	0	(348)
Cash paid for acquisitions, net of cash acquired	0	0	0
Cash received from sale of discontinued operations		0	0
Purchases of investments	0		0
Proceeds from sale of property and equipment	0	0
Change in restricted cash	1,259	(700)	7,964
Net cash used in investing activities - continuing operations	(2,652)	(2,664)	(1,254)
Net cash provided by investing activities - discontinued operations	0	0	0
Total cash used in by investing activities	(2,652)	(2,664)	(1,254)
Cash flows from financing activities:
Proceeds from long-term debt	114,375	690,017	50,000
Debt issuance costs	(6,452)	(14,042)	0
Repayments of long-term debt	(82,176)	(195,217)	(4,375)
Shares repurchased and retired	(97,430)	(91,475)	(241,161)
Proceeds from issuance of shares in connection with share-based compensation	22,569	15,213	28,232
Minimum tax withholding related to net share settlements	(15,230)	(15,980)	(8,665)
Tax benefit related to stock options	6,513	6,791	5,146
Intercompany payments	(36,628)	(610,239)	0
Intercompany proceeds	165,948	179,187	191,147
Net cash provided by/(used in) financing activities - continuing operations	71,489	(35,745)	20,324
Net cash provided by financing activities - discontinued operations	0	0	0
Total cash provided by/(used in) financing activities	71,489	(35,745)	20,324
Effect of Exchange Rate on cash	0	0	0
Net change in cash and cash equivalents	(25,197)	(28,976)	(32,794)
Cash and cash equivalents at beginning of year	61,602	104,310	111,305
Less: Change in cash and cash equivalents of discontinued operations	0	0	0
Plus: Cash swept (to)/from discontinued operations	(8,146)	(13,732)	25,799
Cash and cash equivalents at end of year	28,259	61,602	104,310
Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash (used in)/provided by operating activities - continuing operations	400,950	283,316	354,004
Net cash (used in)/provided by operating activities - discontinued operations	(7,612)	(13,717)	24,094
Total cash (used in)/provided by operating activities	393,338	269,599	378,098
Cash flows from investing activities:
Purchases of property and equipment	(30,810)	(40,598)	(51,660)
Purchases of capitalized data and other intangible assets	(31,063)	(30,077)	(23,171)
Cash paid for acquisitions, net of cash acquired	(146,414)	(665,753)	(92,591)
Cash received from sale of discontinued operations		25,366	2,263
Purchases of investments	(1,684)		(2,351)
Proceeds from sale of property and equipment	137	13,937
Change in restricted cash	0	306	0
Net cash used in investing activities - continuing operations	(209,834)	(696,819)	(167,510)
Net cash provided by investing activities - discontinued operations	0	0	1,862
Total cash used in by investing activities	(209,834)	(696,819)	(165,648)
Cash flows from financing activities:
Proceeds from long-term debt	0	0	1,647
Debt issuance costs	0	0	(10,436)
Repayments of long-term debt	(715)	(4,789)	(291)
Shares repurchased and retired	0	0	0
Proceeds from issuance of shares in connection with share-based compensation	0	0	0
Minimum tax withholding related to net share settlements	0	0	0
Tax benefit related to stock options	0	0	0
Intercompany payments	(165,948)	(179,187)	(180,885)
Intercompany proceeds	0	606,212	0
Net cash provided by/(used in) financing activities - continuing operations	(166,663)	422,236	(189,965)
Net cash provided by financing activities - discontinued operations	0	0	0
Total cash provided by/(used in) financing activities	(166,663)	422,236	(189,965)
Effect of Exchange Rate on cash	0	0	0
Net change in cash and cash equivalents	16,841	(4,984)	22,485
Cash and cash equivalents at beginning of year	8,733	0	3,471
Less: Change in cash and cash equivalents of discontinued operations	(7,612)	(13,717)	25,956
Plus: Cash swept (to)/from discontinued operations	0	0	0
Cash and cash equivalents at end of year	33,186	8,733	0
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash (used in)/provided by operating activities - continuing operations	29,233	42,844	26,080
Net cash (used in)/provided by operating activities - discontinued operations	0	0	1,506
Total cash (used in)/provided by operating activities	29,233	42,844	27,586
Cash flows from investing activities:
Purchases of property and equipment	(9,428)	(9,463)	(8,215)
Purchases of capitalized data and other intangible assets	(5,346)	(5,052)	(14,322)
Cash paid for acquisitions, net of cash acquired	(48,077)	(29,118)	542
Cash received from sale of discontinued operations		0	0
Purchases of investments	(2,064)		0
Proceeds from sale of property and equipment	0	0
Change in restricted cash	175	84	2,104
Net cash used in investing activities - continuing operations	(64,740)	(43,549)	(19,891)
Net cash provided by investing activities - discontinued operations	0	1,536	0
Total cash used in by investing activities	(64,740)	(42,013)	(19,891)
Cash flows from financing activities:
Proceeds from long-term debt	0	0	0
Debt issuance costs	0	0	0
Repayments of long-term debt	0	0	0
Shares repurchased and retired	0	0	0
Proceeds from issuance of shares in connection with share-based compensation	0	0	0
Minimum tax withholding related to net share settlements	0	0	0
Tax benefit related to stock options	0	0	0
Intercompany payments	0	0	(10,262)
Intercompany proceeds	36,628	4,027	0
Net cash provided by/(used in) financing activities - continuing operations	36,628	4,027	(10,262)
Net cash provided by financing activities - discontinued operations	0	0	0
Total cash provided by/(used in) financing activities	36,628	4,027	(10,262)
Effect of Exchange Rate on cash	2,182	(625)	(2,116)
Net change in cash and cash equivalents	3,303	4,233	(4,683)
Cash and cash equivalents at beginning of year	34,342	30,109	34,792
Less: Change in cash and cash equivalents of discontinued operations	0	1,536	1,506
Plus: Cash swept (to)/from discontinued operations	0	1,536	1,506
Cash and cash equivalents at end of year	37,645	34,342	30,109
Consolidating/Eliminating Adjustments [Member]
Cash flows from operating activities:
Net cash (used in)/provided by operating activities - continuing operations	0	0	0
Net cash (used in)/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 discontinued operations		0	0
Purchases of investments	0		0
Proceeds from sale of property and equipment	0	0
Change in restricted cash	0	0	0
Net cash used in investing activities - continuing operations	0	0	0
Net cash provided by investing activities - discontinued operations	0	0	0
Total cash used in by investing activities	0	0	0
Cash flows from financing activities:
Proceeds from long-term debt	0	0	0
Debt issuance costs	0	0	0
Repayments of long-term debt	0	0	0
Shares repurchased and retired	0	0	0
Proceeds from issuance of shares in connection with share-based compensation	0	0	0
Minimum tax withholding related to net share settlements	0	0	0
Tax benefit related to stock options	0	0	0
Intercompany payments	202,576	789,426	191,147
Intercompany proceeds	(202,576)	(789,426)	(191,147)
Net cash provided by/(used in) financing activities - continuing operations	0	0	0
Net cash provided by 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 change 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 (to)/from discontinued operations	0	0	0
Cash and cash equivalents at end of year	$ 0	$ 0	$ 0