| Derivative Instruments, Gain (Loss) [Table Text Block] |
| | | | | | | | | | | | | | | | | | | | Three Months Ended | | Nine Months Ended | | Line Item in the Unaudited Interim Financial Statements | ($ in millions) | October 31, 2015 | | November 1, 2014 | | October 31, 2015 | | November 1, 2014 | | Gain/(loss) recognized in other comprehensive income/(loss) | $ | (10 | ) | | $ | — |
| | $ | (19 | ) | | $ | — |
| | Accumulated other comprehensive income | Gain/(loss) recognized in net income/(loss) | — |
| | — |
| | (2 | ) | | — |
| | Interest expense |
|
| Schedule of Derivative Liabilities at Fair Value [Table Text Block] |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Asset Derivatives at Fair Value | | Liability Derivatives at Fair Value | ($ in millions) | Balance Sheet Location | | October 31, 2015 | | November 1, 2014 | | January 31, 2015 | | Balance Sheet Location | | October 31, 2015 | | November 1, 2014 | | January 31, 2015 | Derivatives designated as hedging instruments: | | | | | | | | | | | | | | | | Interest rate swaps | N/A | | $ | — |
| | $ | — |
| | $ | — |
| | Other accounts payable and accrued expenses | | $ | 2 |
| | $ | — |
| | $ | — |
| Interest rate swaps | N/A | | — |
| | — |
| | — |
| | Other liabilities | | 19 |
| | — |
| | — |
| Total derivatives designated as hedging instruments | | | $ | — |
| | $ | — |
| | $ | — |
| | | | $ | 21 |
| | $ | — |
| | $ | — |
|
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