v3.26.1
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, 2026
Mar. 31, 2025
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Beginning balance $ 29,177 $ 29,027
Other comprehensive income (loss), net of Tax, Portion attributable to parent (211) 254
Ending balance 27,972 28,991
AOCI Attributable to Parent    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Equity, attributable to parent, beginning balance 372 (219)
Beginning balance (95) 55
Beginning balance 277 (164)
OCI, before Reclassifications, before Tax, Attributable to Parent (272) 289
Other comprehensive income (loss) before reclassifications, tax 69 (73)
OCI, before reclassifications, net of tax, attributable to parent (203) 216
Total other comprehensive income (loss) (282) 340
Deferred income taxes and credits 71 (86)
Other comprehensive income (loss), net of Tax, Portion attributable to parent (211) 254
Equity, attributable to parent, ending balance 90 121
Ending balance (24) (31)
Ending balance 66 90
Investment Securities    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Equity, attributable to parent, beginning balance 208 (205)
Beginning balance 155 (153)
OCI, before Reclassifications, before Tax, Attributable to Parent (195) 197
Other comprehensive income (loss) before reclassifications, tax 49 (50)
OCI, before reclassifications, net of tax, attributable to parent (146) 147
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: (4)  
Reclassification from AOCI, current period, tax 1  
Reclassification from AOCI, current period, net of tax, attributable to parent (3)  
Total other comprehensive income (loss) (199) 197
Other comprehensive income (loss), net of Tax, Portion attributable to parent (149) 147
Equity, attributable to parent, ending balance 9 (8)
Ending balance 6 (6)
Cash Flow Hedges    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Equity, attributable to parent, beginning balance 90 (135)
Beginning balance 67 (101)
OCI, before Reclassifications, before Tax, Attributable to Parent (76) 91
Other comprehensive income (loss) before reclassifications, tax 20 (23)
OCI, before reclassifications, net of tax, attributable to parent (56) 68
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: (5) 53
Reclassification from AOCI, current period, tax 1 (13)
Reclassification from AOCI, current period, net of tax, attributable to parent (4) 40
Total other comprehensive income (loss) (81) 144
Other comprehensive income (loss), net of Tax, Portion attributable to parent (60) 108
Equity, attributable to parent, ending balance 9 9
Ending balance 7 7
Defined Benefit Plans    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Equity, attributable to parent, beginning balance 81 131
Beginning balance 61 98
OCI, before Reclassifications, before Tax, Attributable to Parent 0 0
Total other comprehensive income (loss) (1) (2)
Other comprehensive income (loss), net of Tax, Portion attributable to parent (1) (2)
Equity, attributable to parent, ending balance 80 129
Ending balance 60 96
Prior Service Credit    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: (1) (2)
Reclassification from AOCI, current period, tax 0 0
Reclassification from AOCI, current period, net of tax, attributable to parent (1) (2)
Other    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Equity, attributable to parent, beginning balance (7) (10)
Beginning balance (6) (8)
OCI, before Reclassifications, before Tax, Attributable to Parent (1) 1
Other comprehensive income (loss) before reclassifications, tax 0 0
OCI, before reclassifications, net of tax, attributable to parent (1) 1
Total other comprehensive income (loss) (1) 1
Other comprehensive income (loss), net of Tax, Portion attributable to parent (1) 1
Equity, attributable to parent, ending balance (8) (9)
Ending balance $ (7) $ (7)