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Other Comprehensive Income (Loss) - Changes in AOCI by Component (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | Jan. 01, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |  |  |
Equity, beginning balance |  |  | $ 34,569 | $ 40,308 |
Other comprehensive income (loss) before reclassification adjustments, pretax | $ (54) | $ (139) | (33) | (56) |
Tax | (115) | 131 | (135) | 271 |
Other comprehensive income (loss) before reclassification adjustments, net of taxes | (169) | (8) | (168) | 215 |
Reclassification adjustments, pretax | 132 | (15) | 281 | (139) |
Tax | (25) | 9 | (51) | 56 |
Reclassification adjustments, net of taxes | 107 | (6) | 230 | (83) |
Other comprehensive income (loss), net of taxes | (62) | (14) | 62 | 132 |
Reclassification of provisional stranded tax effects (see Note 1) |  |  | (266) |  |
Equity, ending balance | 32,766 | 39,712 | 32,766 | 39,712 |
Derivatives |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |  |  |
Equity, beginning balance | (201) | 106 | (108) | 338 |
Other comprehensive income (loss) before reclassification adjustments, pretax | 265 | (169) | 84 | (432) |
Tax | (56) | 59 | (18) | 151 |
Other comprehensive income (loss) before reclassification adjustments, net of taxes | 209 | (110) | 66 | (281) |
Reclassification adjustments, pretax | 72 | (50) | 164 | (145) |
Tax | (15) | 17 | (34) | 51 |
Reclassification adjustments, net of taxes | 57 | (33) | 130 | (94) |
Other comprehensive income (loss), net of taxes | 266 | (143) | 196 | (375) |
Reclassification of provisional stranded tax effects (see Note 1) |  |  | (23) |  |
Adoption of ASU 2016-01 (see Note 1) |  |  |  |  | $ 0
Equity, ending balance | 65 | (37) | 65 | (37) |
Investments |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |  |  |
Equity, beginning balance | (167) | 40 | (61) | (3) |
Other comprehensive income (loss) before reclassification adjustments, pretax | (17) | 26 | (133) | 113 |
Tax | 0 | 3 | 1 | (4) |
Other comprehensive income (loss) before reclassification adjustments, net of taxes | (17) | 29 | (132) | 109 |
Reclassification adjustments, pretax | 20 | 8 | 36 | (49) |
Tax | 0 | (2) | 0 | 18 |
Reclassification adjustments, net of taxes | 20 | 6 | 36 | (31) |
Other comprehensive income (loss), net of taxes | 3 | 35 | (96) | 78 |
Reclassification of provisional stranded tax effects (see Note 1) |  |  | 1 |  |
Adoption of ASU 2016-01 (see Note 1) |  |  |  |  | (8)
Equity, ending balance | (164) | 75 | (164) | 75 |
Employee Benefit Plans |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |  |  |
Equity, beginning balance | (3,095) | (3,180) | (2,787) | (3,206) |
Other comprehensive income (loss) before reclassification adjustments, pretax | (1) | 29 | (2) | 25 |
Tax | 1 | (3) | 4 | 6 |
Other comprehensive income (loss) before reclassification adjustments, net of taxes | 0 | 26 | 2 | 31 |
Reclassification adjustments, pretax | 40 | 27 | 81 | 55 |
Tax | (10) | (6) | (17) | (13) |
Reclassification adjustments, net of taxes | 30 | 21 | 64 | 42 |
Other comprehensive income (loss), net of taxes | 30 | 47 | 66 | 73 |
Reclassification of provisional stranded tax effects (see Note 1) |  |  | (344) |  |
Adoption of ASU 2016-01 (see Note 1) |  |  |  |  | 0
Equity, ending balance | (3,065) | (3,133) | (3,065) | (3,133) |
Cumulative Translation Adjustment |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |  |  |
Equity, beginning balance | (1,597) | (2,046) | (1,954) | (2,355) |
Other comprehensive income (loss) before reclassification adjustments, pretax | (301) | (25) | 18 | 238 |
Tax | (60) | 72 | (122) | 118 |
Other comprehensive income (loss) before reclassification adjustments, net of taxes | (361) | 47 | (104) | 356 |
Reclassification adjustments, pretax | 0 | 0 | 0 | 0 |
Tax | 0 | 0 | 0 | 0 |
Reclassification adjustments, net of taxes | 0 | 0 | 0 | 0 |
Other comprehensive income (loss), net of taxes | (361) | 47 | (104) | 356 |
Reclassification of provisional stranded tax effects (see Note 1) |  |  | 100 |  |
Adoption of ASU 2016-01 (see Note 1) |  |  |  |  | 0
Equity, ending balance | (1,958) | (1,999) | (1,958) | (1,999) |
Accumulated Other Comprehensive Income (Loss) |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |  |  |
Equity, beginning balance | (5,060) | (5,080) | (4,910) | (5,226) |
Adoption of ASU 2016-01 (see Note 1) |  |  |  |  | $ (8)
Equity, ending balance | $ (5,122) | $ (5,094) | $ (5,122) | $ (5,094) |

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