Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss by Component (Detail) - USD ($)
$ in Millions |
3 Months Ended |
Mar. 31, 2018 |
Mar. 31, 2017 |
| Accumulated Other Comprehensive Income (Loss) [Line Items] |
|
|
|
| Beginning balance |
|
$ (231)
|
$ (234)
|
| Other comprehensive loss before reclassifications |
|
(2)
|
(1)
|
| Amounts reclassified from accumulated other comprehensive loss: |
|
|
|
| Amortization - prior service credit |
|
(9)
|
(11)
|
| Amortization - actuarial loss |
|
9
|
9
|
| Amortization - settlement loss |
|
1
|
0
|
| Tax effect |
|
(1)
|
0
|
| Other comprehensive loss |
|
(2)
|
(3)
|
| Ending balance |
|
(233)
|
(237)
|
| Accumulated Defined Benefit Plans Adjustment | Pension Benefits |
|
|
|
| Accumulated Other Comprehensive Income (Loss) [Line Items] |
|
|
|
| Beginning balance |
|
(190)
|
(233)
|
| Other comprehensive loss before reclassifications |
|
0
|
(1)
|
| Amounts reclassified from accumulated other comprehensive loss: |
|
|
|
| Amortization - prior service credit |
[1] |
(8)
|
(10)
|
| Amortization - actuarial loss |
[1] |
9
|
9
|
| Amortization - settlement loss |
[1] |
1
|
0
|
| Tax effect |
|
(1)
|
0
|
| Other comprehensive loss |
|
1
|
(2)
|
| Ending balance |
|
(189)
|
(235)
|
| Accumulated Defined Benefit Plans Adjustment | Other Benefits |
|
|
|
| Accumulated Other Comprehensive Income (Loss) [Line Items] |
|
|
|
| Beginning balance |
|
(48)
|
(7)
|
| Other comprehensive loss before reclassifications |
|
0
|
0
|
| Amounts reclassified from accumulated other comprehensive loss: |
|
|
|
| Amortization - prior service credit |
[1] |
(1)
|
(1)
|
| Amortization - actuarial loss |
[1] |
0
|
0
|
| Amortization - settlement loss |
|
0
|
0
|
| Tax effect |
|
0
|
0
|
| Other comprehensive loss |
|
(1)
|
(1)
|
| Ending balance |
|
(49)
|
(8)
|
| Gain on Cash Flow Hedge |
|
|
|
| Accumulated Other Comprehensive Income (Loss) [Line Items] |
|
|
|
| Beginning balance |
|
4
|
4
|
| Other comprehensive loss before reclassifications |
|
(2)
|
0
|
| Amounts reclassified from accumulated other comprehensive loss: |
|
|
|
| Tax effect |
|
0
|
0
|
| Other comprehensive loss |
|
(2)
|
0
|
| Ending balance |
|
2
|
4
|
| Workers Compensation |
|
|
|
| Accumulated Other Comprehensive Income (Loss) [Line Items] |
|
|
|
| Beginning balance |
|
3
|
2
|
| Other comprehensive loss before reclassifications |
|
0
|
0
|
| Amounts reclassified from accumulated other comprehensive loss: |
|
|
|
| Tax effect |
|
0
|
0
|
| Other comprehensive loss |
|
0
|
0
|
| Ending balance |
|
$ 3
|
$ 2
|
|
|