Debt - Components of Long Term Debt (Details) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended | 9 Months Ended | |
Aug. 31, 2015 | Oct. 31, 2015 | Aug. 01, 2015 | Nov. 01, 2014 | Oct. 31, 2015 | Nov. 01, 2014 | Jan. 31, 2015 |
Debt Instrument [Line Items] | | | | | | | |
Long-term Debt, Fair Value | | $ 2,900 | | $ 3,100 | $ 2,900 | $ 3,100 | $ 3,100 |
Long-term Debt, Current Maturities | | | $ 317 | | | | |
Unamortized debt discount | | 5 | | 7 | 5 | 7 | 7 |
Deferred Finance Costs, Net | | (18) | | (14) | (18) | (14) | (13) |
Long-term debt | | 2,792 | | 2,779 | 2,792 | 2,779 | 2,780 |
Repayments of Debt | | (318) | 767 | | | | |
Gains (Losses) on Extinguishment of Debt | | 38 | 131 | 0 | 169 | 0 | |
Payments of Debt Extinguishment Costs | | | 126 | | $ 163 | 0 | |
Redemption Premium | $ (37) | | | | | | |
Write off of Deferred Debt Issuance Cost | $ 1 | | 5 | | | | |
Line of Credit Facility, Description | | | | | 1 | | |
Short-term Debt | | $ 400 | | 0 | $ 400 | 0 | 0 |
Senior Notes Due Twenty Twenty Five [Member] | Senior Notes | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Total senior debt | | | $ 650 | | | | |
Senior Notes | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Effective Rate | | 5.00% | | | 5.00% | | |
Total senior debt | | $ 2,815 | | 2,800 | $ 2,815 | 2,800 | 2,800 |
Senior Notes | Senior Notes Due 2017 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Effective Rate | | 0.00% | | | 0.00% | | |
Debt Instrument, Interest Rate, Stated Percentage | | 0.00% | 6.00% | | 0.00% | | |
Total senior debt | | $ 0 | | 650 | $ 0 | 650 | 650 |
Senior Notes | Senior Notes Due Two Thousand And Twenty One [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Effective Rate | | 5.00% | | | 5.00% | | |
Debt Instrument, Interest Rate, Stated Percentage | | 4.00% | | | 4.00% | | |
Total senior debt | | $ 650 | | 650 | $ 650 | 650 | 650 |
Senior Notes | Senior Notes Due 2023 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Effective Rate | | 3.00% | | | 3.00% | | |
Debt Instrument, Interest Rate, Stated Percentage | | 3.00% | | | 3.00% | | |
Total senior debt | | $ 350 | | 350 | $ 350 | 350 | 350 |
Senior Notes | Senior Notes Due Twenty Twenty Three [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Effective Rate | | 5.00% | | | 5.00% | | |
Debt Instrument, Interest Rate, Stated Percentage | | 5.00% | | | 5.00% | | |
Total senior debt | | $ 300 | | 300 | $ 300 | 300 | 300 |
Senior Notes | Senior Notes Due Twenty Twenty Five [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Effective Rate | | 4.00% | | | 4.00% | | |
Debt Instrument, Interest Rate, Stated Percentage | | 4.00% | 4.00% | | 4.00% | | |
Total senior debt | | $ 650 | | 0 | $ 650 | 0 | 0 |
Senior Notes | Senior Notes Due 2029 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Effective Rate | | 7.00% | | | 7.00% | | |
Debt Instrument, Interest Rate, Stated Percentage | | 7.00% | | | 7.00% | | |
Total senior debt | | $ 99 | | 200 | $ 99 | 200 | 200 |
Senior Notes | Senior Notes Due 2033 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Effective Rate | | 6.00% | | | 6.00% | | |
Debt Instrument, Interest Rate, Stated Percentage | | 6.00% | | | 6.00% | | |
Total senior debt | | $ 166 | | 300 | $ 166 | 300 | 300 |
Senior Notes | Senior Notes Due 2037 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Effective Rate | | 7.00% | | | 7.00% | | |
Debt Instrument, Interest Rate, Stated Percentage | | 7.00% | | | 7.00% | | |
Total senior debt | | $ 150 | | 350 | $ 150 | 350 | 350 |
Senior Notes | Senior Notes Due 2045 | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Effective Rate | | 6.00% | | | 6.00% | | |
Debt Instrument, Interest Rate, Stated Percentage | | 6.00% | 6.00% | | 6.00% | | |
Total senior debt | | $ 450 | $ 450 | $ 0 | $ 450 | $ 0 | $ 0 |