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 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Beginning balance $ 27,972 $ 28,991 $ 29,177 $ 29,027
Other comprehensive income (loss), net of Tax, Portion attributable to parent (158) 125 (369) 379
Ending balance 27,946 28,525 27,946 28,525
AOCI Attributable to Parent        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Equity, attributable to parent, beginning balance 90 121 372 (219)
Beginning balance (24) (31) (95) 55
Beginning balance 66 90 277 (164)
OCI, before Reclassifications, before Tax, Attributable to Parent (203) 137 (475) 426
Other comprehensive income (loss) before reclassifications, tax 51 (35) 120 (108)
OCI, before reclassifications, net of tax, attributable to parent (152) 102 (355) 318
Total other comprehensive income (loss) (213) 168 (495) 508
Deferred income taxes and credits 55 (43) 126 (129)
Other comprehensive income (loss), net of Tax, Portion attributable to parent (158) 125 (369) 379
Equity, attributable to parent, ending balance (123) 289 (123) 289
Ending balance 31 (74) 31 (74)
Ending balance (92) 215 (92) 215
Investment Securities        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Equity, attributable to parent, beginning balance 9 (8) 208 (205)
Beginning balance 6 (6) 155 (153)
OCI, before Reclassifications, before Tax, Attributable to Parent (134) 90 (329) 287
Other comprehensive income (loss) before reclassifications, tax 35 (23) 84 (73)
OCI, before reclassifications, net of tax, attributable to parent (99) 67 (245) 214
Amounts reclassified from accumulated other comprehensive income (loss) 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) (134) 90 (333) 287
Other comprehensive income (loss), net of Tax, Portion attributable to parent (99) 67 (248) 214
Equity, attributable to parent, ending balance (125) 82 (125) 82
Ending balance (93) 61 (93) 61
Cash Flow Hedges        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Equity, attributable to parent, beginning balance 9 9 90 (135)
Beginning balance 7 7 67 (101)
OCI, before Reclassifications, before Tax, Attributable to Parent (69) 43 (145) 134
Other comprehensive income (loss) before reclassifications, tax 16 (11) 36 (34)
OCI, before reclassifications, net of tax, attributable to parent (53) 32 (109) 100
Amounts reclassified from accumulated other comprehensive income (loss) that (increase) decrease net income: (8) 33 (13) 86
Reclassification from AOCI, current period, tax 3 (9) 4 (22)
Reclassification from AOCI, current period, net of tax, attributable to parent (5) 24 (9) 64
Total other comprehensive income (loss) (77) 76 (158) 220
Other comprehensive income (loss), net of Tax, Portion attributable to parent (58) 56 (118) 164
Equity, attributable to parent, ending balance (68) 85 (68) 85
Ending balance (51) 63 (51) 63
Defined Benefit Plans        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Equity, attributable to parent, beginning balance 80 129 81 131
Beginning balance 60 96 61 98
OCI, before Reclassifications, before Tax, Attributable to Parent 0 0 0 0
Total other comprehensive income (loss) (2) (2) (3) (4)
Other comprehensive income (loss), net of Tax, Portion attributable to parent (1) (1) (2) (3)
Equity, attributable to parent, ending balance 78 127 78 127
Ending balance 59 95 59 95
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) (2) (3) (4)
Reclassification from AOCI, current period, tax 1 1 1 1
Reclassification from AOCI, current period, net of tax, attributable to parent (1) (1) (2) (3)
Other        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Equity, attributable to parent, beginning balance (8) (9) (7) (10)
Beginning balance (7) (7) (6) (8)
OCI, before Reclassifications, before Tax, Attributable to Parent 0 4 (1) 5
Other comprehensive income (loss) before reclassifications, tax   (1) 0 (1)
OCI, before reclassifications, net of tax, attributable to parent   3 (1) 4
Total other comprehensive income (loss) 0 4 (1) 5
Other comprehensive income (loss), net of Tax, Portion attributable to parent 0 3 (1) 4
Equity, attributable to parent, ending balance (8) (5) (8) (5)
Ending balance $ (7) $ (4) $ (7) $ (4)