Condensed Consolidated Statements of Equity (Unaudited) (USD $) In Thousands, except Share data	Total	Common Stock, Class A	Common Stock, Class B	Additional Paid-in Capital	Contingent Consideration [Member]	Retained Earnings	Other Comprehensive Income (Loss)	Non- Controlling Interest
Balance at Dec. 31, 2009	$ 979,869	$ 1	$ 0	$ 730,941	$ 0	$ 33,704	$ (11,198)	$ 226,421
Balance, shares at Dec. 31, 2009		90,423,941	24,752,955
Equity-based compensation expense	7,847			6,260				1,587
Issuance of shares in connection with equity compensation plans, net of taxes	32	0		113			(1)	(80)
Issuance of shares in connection with equity compensation plans, net of taxes, gross, shares		39,582
Exchange of units of EBS Master for Class A common stock, net of taxes	82	0	0	425			(4)	(339)
Exchange of units of EBS Master for Class A common stock, net of taxes, shares		36,829	(36,829)
Cancellation of Class B common stock, net of taxes	(72)			127			(2)	(197)
Cancellation of Class B common stock, net of taxes, shares			(26,984)
Issuance of Class A common stock in connection with acquisitions, net of taxes	7,813			4,279	2,667		(7)	874
Issuance of Class A common stock in connection with acquisitions, net of taxes, shares		361,558
Tax receivable agreements with related parties, net of taxes	(89)			(89)
Contribution of data sublicense intangible to EBS Master	497			(861)				1,358
Other	100			100
Comprehensive income:
Net income	11,517					6,118		5,399
Change in the fair value of interest rate swap, net of taxes	3,892						3,058	834
Foreign currency translation adjustment	51						41	10
Other comprehensive income amortization, net of taxes	2,541						1,997	544
Total comprehensive income	18,001
Balance at Jun. 30, 2010	1,014,080	1	0	741,295	2,667	39,822	(6,116)	236,411
Balance, shares at Jun. 30, 2010		90,861,910	24,689,142
Balance at Dec. 31, 2010	1,055,288	1	0	738,888	1,955	53,250	(2,569)	263,763
Balance, shares at Dec. 31, 2010		91,064,486	24,689,142
Equity-based compensation expense	11,483			9,116				2,367
Issuance of shares in connection with equity compensation plans, net of taxes	1,255	0		1,590			0	(335)
Issuance of shares in connection with equity compensation plans, net of taxes, gross, shares		144,096
Tax receivable agreements with related parties, net of taxes	(58)			(58)
Comprehensive income:
Net income	16,503					10,194		6,309
Foreign currency translation adjustment	(5)						(4)	(1)
Other comprehensive income amortization, net of taxes	1,643						1,293	350
Total comprehensive income	18,141
Balance at Jun. 30, 2011	$ 1,086,109	$ 1	$ 0	$ 749,536	$ 1,955	$ 63,444	$ (1,280)	$ 272,453
Balance, shares at Jun. 30, 2011		91,208,582	24,689,142