Summary of Significant Accounting Policies Consolidated Statement of Operations Restatement (Details) (USD $) In Thousands, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Revenue	$ 612,401	$ 567,339	$ 1,176,092	$ 1,064,962
Cost of revenues	421,318	393,283	800,899	733,842
Gross profit	191,083	174,056	375,193	331,120
Operating income	48,085	50,009	98,174	81,628
Income before income taxes	34,356	35,730	71,043	52,001
Income tax (provision) benefit	80	(10,419)	(9,487)	(1,440)
Net income	34,436	25,311	61,556	50,561
Earnings per common share-Basic	$ 0.85	$ 0.63	$ 1.52	$ 1.26
Earnings per common share-Diluted	$ 0.84	$ 0.61	$ 1.50	$ 1.23
Scenario, Previously Reported [Member]
Revenue		569,460		1,068,740
Cost of revenues		393,136		733,521
Gross profit		176,324		335,219
Operating income		52,277		85,727
Income before income taxes		37,998		56,100
Income tax (provision) benefit		(11,098)		(2,413)
Net income		26,900		53,687
Earnings per common share-Basic		$ 0.67		$ 1.33
Earnings per common share-Diluted		$ 0.65		$ 1.31
As restated [Member]
Revenue		567,339		1,064,962
Cost of revenues		393,283		733,842
Gross profit		174,056		331,120
Operating income		50,009		81,628
Income before income taxes		35,730		52,001
Income tax (provision) benefit		(10,419)		(1,440)
Net income		$ 25,311		$ 50,561
Earnings per common share-Basic		$ 0.63		$ 1.26
Earnings per common share-Diluted		$ 0.61		$ 1.23