Debt - Long-Term Debt (Details) - USD ($)	1 Months Ended		12 Months Ended
	Jul. 31, 2013	Mar. 31, 2011	Jan. 30, 2016	Jan. 31, 2015	Jul. 16, 2013
Long-term Debt.
Total long-term debt			$ 1,525,000,000	$ 1,502,000,000
Financing Lease Obligations			178,000,000	69,000,000
Long-term Debt and Capital Lease Obligations, Including Current Maturities			1,734,000,000	1,613,000,000
Less: current portion			(395,000,000)	(41,000,000)
Long-term Debt, Excluding Current Maturities			1,339,000,000	1,572,000,000
Long-term debt, fair value			1,543,000,000	1,494,000,000
Future maturities of long-term debt, including capitalized leases
2017			350,000,000
2018			0
2019			517,000,000
2020			0
2021			0
Thereafter			$ 658,000,000
2016 and 2021 Notes [Member]
Long-term Debt.
Underwriting discounts		$ 6,000,000
Net proceeds from the sale of the Notes		990,000,000
Redemption price, as percentage of principal amount of debt instrument (as a percent)			100.00%
Redemption price upon control triggering event, percentage of principal amount (as a percent)			101.00%
2016 Notes [Member]
Long-term Debt.
Total long-term debt			$ 350,000,000	350,000,000
Debt instrument issued, principal amount		350,000,000
Interest rate (as a percent)			3.75%
Notes due 2018 [Member]
Long-term Debt.
Total long-term debt			$ 500,000,000	500,000,000
Debt instrument issued, principal amount					$ 500,000,000
Interest rate (as a percent)					5.00%
Underwriting discounts	$ 5,000,000
Net proceeds from the sale of the Notes	$ 495,000,000
Redemption price upon control triggering event, percentage of principal amount (as a percent)			101.00%
2021 Notes [Member]
Long-term Debt.
Total long-term debt			$ 650,000,000	650,000,000
Debt instrument issued, principal amount		$ 650,000,000
Interest rate (as a percent)			5.50%
Interest Rate Swap [Member]
Long-term Debt.
Total long-term debt			$ 25,000,000	1,000,000
Capital Lease Obligations [Member]
Long-term Debt.
Total long-term debt			38,000,000	52,000,000
Debt discounts and issuance costs [Member]
Long-term Debt.
Total long-term debt			(7,000,000)	(10,000,000)
Other debt [Member]
Long-term Debt.
Total long-term debt			$ 0	$ 1,000,000
Notes due 2018 [Member]
Long-term Debt.
Redemption price, as percentage of principal amount of debt instrument (as a percent)			100.00%
Debt Instrument, Treasury Rate Basis Points for Redemption			50