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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 | 3 Months Ended
--- | ---
Mar. 31, 2025 | Mar. 31, 2024
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Beginning balance | $ 29,027 | $ 26,957
Ending balance | 28,991 | 27,169
AOCI Attributable to Parent |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Equity, attributable to parent, beginning balance | (219) | (616)
Beginning balance | 55 | 157
Beginning balance | (164) | (459)
Other comprehensive income (loss) before reclassifications: | 289 | (258)
Other comprehensive income (loss) before reclassifications, tax | (73) | 62
OCI, before reclassifications, net of tax, attributable to parent | 216 | (196)
Total other comprehensive income (loss) | 340 | (171)
Deferred income taxes and credits | (86) | 41
Other comprehensive income (loss), net of Tax, Portion attributable to parent | 254 | (130)
Equity, attributable to parent, ending balance | 121 | (787)
Ending balance | (31) | 198
Ending balance | 90 | (589)
Investment Securities |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Equity, attributable to parent, beginning balance | (205) | (251)
Beginning balance | (153) |
Other comprehensive income (loss) before reclassifications: | 197 | (13)
Other comprehensive income (loss) before reclassifications, tax | (50) | 2
OCI, before reclassifications, net of tax, attributable to parent | 147 | (11)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: |  | 1
Reclassification from AOCI, current period, net of tax, attributable to parent |  | 1
Total other comprehensive income (loss) | 197 | (12)
Equity, attributable to parent, ending balance | (8) | (263)
Ending balance | (6) |
Cash Flow Hedges |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Equity, attributable to parent, beginning balance | (135) | (203)
Beginning balance | (101) |
Other comprehensive income (loss) before reclassifications: | 91 | (243)
Other comprehensive income (loss) before reclassifications, tax | (23) | 60
OCI, before reclassifications, net of tax, attributable to parent | 68 | (183)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: | 53 | 87
Reclassification from AOCI, current period, tax | (13) | (21)
Reclassification from AOCI, current period, net of tax, attributable to parent | 40 | 66
Total other comprehensive income (loss) | 144 | (156)
Equity, attributable to parent, ending balance | 9 | (359)
Ending balance | 7 |
Defined Benefit Plans |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Equity, attributable to parent, beginning balance | 131 | (155)
Beginning balance | 98 |
Other comprehensive income (loss) before reclassifications: | 0 | 0
Total other comprehensive income (loss) | (2) | (1)
Equity, attributable to parent, ending balance | 129 | (156)
Ending balance | 96 |
Actuarial Gains |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Amounts reclassified from accumulated other comprehensive income 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)
Other |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Equity, attributable to parent, beginning balance | (10) | (7)
Beginning balance | (8) |
Other comprehensive income (loss) before reclassifications: | 1 | (2)
Other comprehensive income (loss) before reclassifications, tax | 0 | 0
OCI, before reclassifications, net of tax, attributable to parent | 1 | (2)
Total other comprehensive income (loss) | 1 | (2)
Equity, attributable to parent, ending balance | (9) | $ (9)
Ending balance | $ (7) |

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