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Comprehensive Income - Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income (Detail) - USD ($) $ in Millions | 9 Months Ended
--- | ---
Sep. 30, 2024 | Sep. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Beginning balance | $ 26,957 | $ 25,318
Ending balance | 28,876 | 26,196
AOCI Attributable to Parent |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Equity, attributable to parent, beginning balance | (616) | (1,066)
Beginning balance | 157 | 276
Beginning balance | (459) | (790)
Other comprehensive income (loss) before reclassifications: | 284 | (368)
Other comprehensive income (loss) before reclassifications, tax | (72) | 92
OCI, before reclassifications, net of tax, attributable to parent | 212 | (276)
Total other comprehensive income (loss) | 580 | (200)
Deferred income taxes and credits | (148) | 48
Other comprehensive income (loss), net of Tax, Portion attributable to parent | 432 | (152)
Equity, attributable to parent, ending balance | (36) | (1,266)
Ending balance | 9 | 324
Ending balance | (27) | (942)
Investment Securities |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Equity, attributable to parent, beginning balance | (251) | (444)
Beginning balance | (187) |
Other comprehensive income (loss) before reclassifications: | 307 | (2)
Other comprehensive income (loss) before reclassifications, tax | (78) | 1
OCI, before reclassifications, net of tax, attributable to parent | 229 | (1)
Amounts reclassified from accumulated other comprehensive income (loss) that (increase) decrease net income: | 13 |
Reclassification from AOCI, current period, tax | (4) |
Reclassification from AOCI, current period, net of tax, attributable to parent | 9 |
Total other comprehensive income (loss) | 320 | (2)
Equity, attributable to parent, ending balance | 69 | (446)
Ending balance | 51 |
Cash Flow Hedges |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Equity, attributable to parent, beginning balance | (203) | (336)
Beginning balance | (151) |
Other comprehensive income (loss) before reclassifications: | (26) | (366)
Other comprehensive income (loss) before reclassifications, tax | 7 | 91
OCI, before reclassifications, net of tax, attributable to parent | (19) | (275)
Amounts reclassified from accumulated other comprehensive income (loss) that (increase) decrease net income: | 288 | 173
Reclassification from AOCI, current period, tax | (73) | (44)
Reclassification from AOCI, current period, net of tax, attributable to parent | 215 | 129
Total other comprehensive income (loss) | 262 | (193)
Equity, attributable to parent, ending balance | 59 | (529)
Ending balance | 45 |
Defined Benefit Plans |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Equity, attributable to parent, beginning balance | (155) | (273)
Beginning balance | (115) |
Other comprehensive income (loss) before reclassifications: | 0 | 0
Total other comprehensive income (loss) | (5) | (5)
Equity, attributable to parent, ending balance | (160) | (278)
Ending balance | (119) |
Prior Service Credit |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Amounts reclassified from accumulated other comprehensive income (loss) that (increase) decrease net income: | (2) | (1)
Reclassification from AOCI, current period, tax | 0 | 0
Reclassification from AOCI, current period, net of tax, attributable to parent | (2) | (1)
Actuarial Gains |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Amounts reclassified from accumulated other comprehensive income (loss) that (increase) decrease net income: | (3) | (4)
Reclassification from AOCI, current period, tax | 1 | 0
Reclassification from AOCI, current period, net of tax, attributable to parent | (2) | (4)
Other |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Equity, attributable to parent, beginning balance | (7) | (13)
Beginning balance | (6) |
Other comprehensive income (loss) before reclassifications: | 3 | 0
Other comprehensive income (loss) before reclassifications, tax | (1) |
OCI, before reclassifications, net of tax, attributable to parent | 2 |
Total other comprehensive income (loss) | 3 | 0
Equity, attributable to parent, ending balance | (4) | $ (13)
Ending balance | $ (4) |

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