v3.26.1
Accumulated Other Comprehensive Income - Schedule of Changes in AOCI (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Beginning balance $ 20,381 $ 18,176
Other comprehensive income before reclassification, net of income taxes (291) 610
Amounts reclassified from AOCI, net of income taxes 30 73
Total other comprehensive income (loss), net of tax (261) 683
Ending balance 19,987 19,003
Accumulated Other Comprehensive Income (Loss)    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Beginning balance (1,960) (3,470)
Ending balance (2,221) (2,787)
Unrealized gains (losses) on securities available for sale    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Beginning balance (1,716) (2,734)
Other comprehensive income before reclassification, net of income taxes (172) 424
Amounts reclassified from AOCI, net of income taxes 0 0
Total other comprehensive income (loss), net of tax (172) 424
Ending balance (1,888) (2,310)
Unrealized gains (losses) on derivative financial instruments    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Beginning balance (7) (434)
Other comprehensive income before reclassification, net of income taxes (119) 122
Amounts reclassified from AOCI, net of income taxes 28 71
Total other comprehensive income (loss), net of tax (91) 193
Ending balance (98) (241)
Net pension and postretirement benefit costs    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Beginning balance (237) (302)
Other comprehensive income before reclassification, net of income taxes 0 64
Amounts reclassified from AOCI, net of income taxes 2 2
Total other comprehensive income (loss), net of tax 2 66
Ending balance $ (235) $ (236)