Retirement Benefit Plans (Level 3 Investment Assets) (Details)
$ in Millions |
12 Months Ended |
|
Jan. 30, 2016
USD ($)
manager
|
Jan. 31, 2015
USD ($)
|
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |
|
|
| Number of hedge fund managers (more than) | manager |
30
|
|
| Corporate bonds [Member] |
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
| Balance, beginning of year |
$ 7
|
$ 11
|
| Transfers, net |
0
|
|
| Realized gains |
(3)
|
0
|
| Unrealized gains/(losses) |
2
|
(1)
|
| Purchases and issuances |
1
|
5
|
| Sales, maturities and settlements |
(2)
|
(8)
|
| Balance, end of year |
5
|
7
|
| Corporate loans [Member] |
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
| Balance, beginning of year |
5
|
6
|
| Transfers, net |
0
|
|
| Realized gains |
0
|
0
|
| Unrealized gains/(losses) |
0
|
0
|
| Purchases and issuances |
0
|
4
|
| Sales, maturities and settlements |
(2)
|
(5)
|
| Balance, end of year |
3
|
5
|
| Hedge Funds [Member] |
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
| Balance, beginning of year |
314
|
153
|
| Transfers, net |
0
|
|
| Realized gains |
3
|
13
|
| Unrealized gains/(losses) |
(1)
|
(4)
|
| Purchases and issuances |
119
|
467
|
| Sales, maturities and settlements |
(221)
|
(315)
|
| Balance, end of year |
214
|
314
|
| Private Equity Funds [Member] |
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
| Balance, beginning of year |
281
|
298
|
| Transfers, net |
0
|
|
| Realized gains |
41
|
57
|
| Unrealized gains/(losses) |
(17)
|
(8)
|
| Purchases and issuances |
18
|
31
|
| Sales, maturities and settlements |
(75)
|
(97)
|
| Balance, end of year |
248
|
281
|
| Private real estate [Member] |
|
|
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |
|
|
| Balance, beginning of year |
153
|
204
|
| Transfers, net |
0
|
|
| Realized gains |
(23)
|
3
|
| Unrealized gains/(losses) |
38
|
17
|
| Purchases and issuances |
2
|
3
|
| Sales, maturities and settlements |
(19)
|
(74)
|
| Balance, end of year |
$ 151
|
$ 153
|