Employee Benefit Plans (Details) - USD ($) |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
Sep. 30, 2017 |
Sep. 30, 2016 |
|
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Pension Contributions | $ 2,008,000,000 | $ 125,000,000 | ||
| Contributions - Defined benefit plans | $ 1,929,000,000 | $ 18,000,000 | 2,008,000,000 | 125,000,000 |
| Contributions - Defined contribution plans | 86,000,000 | 79,000,000 | 262,000,000 | 235,000,000 |
| Domestic Plan [Member] | ||||
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Pension Contributions | 1,900,000,000 | 0 | 1,900,000,000 | 0 |
| Pension Plan [Member] | ||||
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Service cost | 94,000,000 | 96,000,000 | 280,000,000 | 287,000,000 |
| Interest cost | 281,000,000 | 302,000,000 | 838,000,000 | 908,000,000 |
| Expected return on plan assets | 555,000,000 | 554,000,000 | 1,636,000,000 | 1,669,000,000 |
| Amortization of prior service credit | (9,000,000) | (7,000,000) | (27,000,000) | (22,000,000) |
| Recognized actuarial net loss (gain) | (144,000,000) | (135,000,000) | (430,000,000) | (406,000,000) |
| Net settlement and curtailment (gain) loss | (2,000,000) | (3,000,000) | (1,000,000) | (18,000,000) |
| Total net periodic benefit (income) cost | (43,000,000) | (25,000,000) | (114,000,000) | (72,000,000) |
| Defined Benefit Plan, Accumulated Benefit Obligation, Increase (Decrease) for Plan Amendment | (170,000,000) | |||
| Other Postretirement Benefits Plan [Member] | ||||
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Service cost | 0 | 1,000,000 | 2,000,000 | 3,000,000 |
| Interest cost | 9,000,000 | 9,000,000 | 22,000,000 | 25,000,000 |
| Expected return on plan assets | 0 | 0 | 0 | 0 |
| Amortization of prior service credit | (1,000,000) | 0 | (1,000,000) | 0 |
| Recognized actuarial net loss (gain) | 2,000,000 | 1,000,000 | 7,000,000 | 3,000,000 |
| Net settlement and curtailment (gain) loss | 0 | 0 | 0 | 0 |
| Total net periodic benefit (income) cost | $ 6,000,000 | $ 9,000,000 | $ 16,000,000 | $ 25,000,000 |