CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Consolidated Statements of Operations [Abstract]
Revenues (including amounts from related parties of $13,882, $49,788 and $60,192 for the years ended December 31, 2011, 2010 and 2009, respectively)	$ 1,331,840	[1]	$ 1,138,343	[1]	$ 1,027,104	[1]
Expenses:
Cost of revenues (exclusive of items shown separately below)	533,735		463,473		491,294
Selling, general and administrative	209,469		166,374		162,604
Depreciation and amortization of fixed assets	43,827		40,728		38,578
Amortization of intangible assets	34,792		27,398		32,621
Acquisition related liabilities adjustment	(3,364)		(544)		0
Total expenses	818,459		697,429		725,097
Operating income	513,381		440,914		302,007
Other income/(expense):
Investment income	201		305		195
Realized gain/(loss) on securities, net	686		95		(2,332)
Interest expense	(53,847)		(34,664)		(35,265)
Total other expense, net	(52,960)		(34,264)		(37,402)
Income before income taxes	460,421		406,650		264,605
Provision for income taxes	(177,663)		(164,098)		(137,991)
Net income	$ 282,758		$ 242,552		$ 126,614
Basic net income per share	$ 1.70		$ 1.36		$ 0.72
Diluted net income per share	$ 1.63		$ 1.30		$ 0.70
Weighted average shares outstanding:
Basic	166,015,238		177,733,503		174,767,795
Diluted	173,325,110		186,394,962		182,165,661

[1] See Note 19. Related Parties for further information.