Debt (Debt Covenant Compliance) (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Jul. 26, 2011
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	$ 1,300,000,000
Ratio of Indebtedness to Net Capital	2.18
Ratio of Interest Coverage	6.96
Fixed Charge Coverage Ratio	3.52
Net Worth, Under Convenant Compliance	1,280,000,000
Financing Agreement July 2011 [Member]
Debt Instrument [Line Items]
Debt financing agreement		1,500,000,000
Debt Instrument, Covenant Compliance, Payment Restrictions, Ratio of Indebtedness to Net Capital Threshold	3
Debt Instrument, Covenant Compliance, Payment Limitations To Be Imposed If Ratio of Net Capital to Indebtedness Exceeds Threshold	120,000,000
Debt Instrument, Covenant Compliance, Payment Limitations To Be Imposed If Ratio of Net Capital to Indebtedness Below Threshold	0
Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Covenant Compliance, Ratio of Indebtedness to Net Capital	3.50
Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Covenant Compliance, Ratio of Interest Coverage	3.25
Debt Instrument, Covenant Compliance, Fixed Charge Coverage Ratio	1.50
Debt Instrument, Covenant Compliance, Consolidated Net Worth Threshold	$ 745,800,000
Debt Instrument, Covenant Compliance, Consolidated Net Income Threshold, Percentage	40.00%