Retirement Benefit Plans (Net Periodic Expense) (Details) - USD ($)
$ in Millions |
3 Months Ended |
9 Months Ended |
|
|
Oct. 28, 2017 |
Oct. 29, 2016 |
Oct. 28, 2017 |
Oct. 29, 2016 |
Mar. 31, 2017 |
Jan. 28, 2017 |
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |
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| Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate |
3.94%
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3.94%
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|
4.34%
|
4.40%
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| Net periodic benefit expense/(income) |
$ 9
|
$ 1
|
$ 3
|
$ 5
|
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| Other Postretirement Benefits Plan [Member] |
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| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |
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| Net periodic benefit expense/(income) |
|
(6)
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(14)
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| Primary Pension Plan |
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| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |
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| Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement |
$ (195)
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| Defined Benefit Plan, Funded Status of Plan, Percent |
100.00%
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|
100.00%
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|
98.00%
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|
| Service cost |
$ 11
|
14
|
$ 32
|
41
|
|
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| Interest cost |
36
|
38
|
109
|
114
|
|
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| Expected return on plan assets |
(53)
|
(54)
|
(160)
|
(161)
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| Amortization of prior service cost/(credit) |
1
|
2
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5
|
6
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| Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement |
(12)
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(12)
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| Net periodic benefit expense/(income) |
7
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0
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(2)
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0
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| Supplemental Pension Plans |
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| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |
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| Service cost |
0
|
0
|
0
|
0
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| Interest cost |
2
|
1
|
5
|
5
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| Net periodic benefit expense/(income) |
2
|
1
|
5
|
5
|
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| Primary and Supplemental Pension Plans Total [Member] |
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| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |
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| Service cost |
11
|
14
|
32
|
41
|
|
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| Interest cost |
38
|
39
|
114
|
119
|
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|
| Expected return on plan assets |
(53)
|
(54)
|
(160)
|
(161)
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|
|
| Amortization of prior service cost/(credit) |
1
|
2
|
5
|
6
|
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| Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement |
(12)
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(12)
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| Net periodic benefit expense/(income) |
$ 9
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$ 1
|
$ 3
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$ 5
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