Debt Narrative (Details) (USD $)	3 Months Ended			6 Months Ended												0 Months Ended
	Jun. 30, 2012		Jun. 30, 2011	Jun. 30, 2012		Jun. 30, 2011	Jun. 30, 2012 Revolving Credit Facility		Mar. 16, 2012 Line of Credit Credit Agreement	Mar. 16, 2012 Line of Credit Revolving Credit Facility	Mar. 16, 2012 Line of Credit Revolving Credit Facility Minimum	Mar. 16, 2012 Line of Credit Revolving Credit Facility Maximum	Mar. 16, 2012 Line of Credit Senior Secured Term Loan Payable Through 2017	Mar. 16, 2012 Line of Credit Senior Secured Term Loan Payable Through 2017 Minimum	Mar. 16, 2012 Line of Credit Senior Secured Term Loan Payable Through 2017 Maximum	Mar. 16, 2012 Line of Credit Senior Secured Term Loan Payable Through 2014 - A Senior Secured Term Loan Payable Through 2014 - B	Mar. 16, 2012 Term Loan Facility Senior Secured Term Loan Payable Through 2017
Credit Agreement
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,017,800,000			$ 1,017,800,000			$ 1,000,000,000		$ 2,000,000,000	$ 1,000,000,000							$ 1,000,000,000
Credit facility, Variable rate, Spread over LIBOR										2.25%	1.75%	2.75%	2.25%	1.75%	2.75%
Line of Credit Facility, Amount Outstanding	396,600,000			396,600,000			384,700,000		1,530,000,000
Early Repayment of Senior Debt																1,680,000,000
Undrawn capacity	589,000,000	[1]		589,000,000	[1]		583,100,000	[1]		475,000,000
Gains (losses) on modification or extinguishment of Debt	$ 0		$ (800,000)	$ (8,900,000)		$ (800,000)										$ (8,900,000)

[1] In accordance with its debt agreements, the Company’s availability under its Revolving Credit Facility has been reduced by the amount of standby letters of credit issued of $32.2 million as of June 30, 2012. These letters of credit are used primarily as security against its self-insurance obligations and workers’ compensation obligations. These letters of credit expire at various dates through 2013 unless extended.