v3.25.1
AOCI (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
AOCI, Net of Tax [Roll Forward]    
Total OCI, net of tax $ 963 $ (716)
Pension and OPEB Costs    
AOCI, Net of Tax [Roll Forward]    
AOCI, beginning balance (648) (1,079)
OCI before reclassifications, net of tax 5 1
Total OCI, net of tax 5 1
AOCI, ending balance (643) (1,078)
Pension and OPEB Costs | Amounts reclassified from AOCI    
Amounts reclassified from AOCI:    
Before tax 0 0
Tax effect 0 0
Amounts reclassified, net of tax 0 0
Cash Flow Hedges    
AOCI, Net of Tax [Roll Forward]    
AOCI, beginning balance (861) (300)
OCI before reclassifications, net of tax 358 (232)
Total OCI, net of tax 429 (190)
AOCI, ending balance (432) (490)
Cash Flow Hedges | Amounts reclassified from AOCI    
Amounts reclassified from AOCI:    
Before tax 93 55
Tax effect 22 13
Amounts reclassified, net of tax 71 42
AFS Securities    
AOCI, Net of Tax [Roll Forward]    
AOCI, beginning balance (4,573) (8,778)
OCI before reclassifications, net of tax 543 (455)
Total OCI, net of tax 478 (576)
AOCI, ending balance (4,095) (9,354)
AFS Securities | Amounts reclassified from AOCI    
Amounts reclassified from AOCI:    
Before tax (85) (158)
Tax effect (20) (37)
Amounts reclassified, net of tax (65) (121)
HTM Securities    
AOCI, Net of Tax [Roll Forward]    
AOCI, beginning balance (2,125) (2,347)
OCI before reclassifications, net of tax 0 0
Total OCI, net of tax 50 51
AOCI, ending balance (2,075) (2,296)
HTM Securities | Amounts reclassified from AOCI    
Amounts reclassified from AOCI:    
Before tax 65 66
Tax effect 15 15
Amounts reclassified, net of tax 50 51
Other, net    
AOCI, Net of Tax [Roll Forward]    
AOCI, beginning balance (6) (2)
OCI before reclassifications, net of tax 1 (2)
Total OCI, net of tax 1 (2)
AOCI, ending balance (5) (4)
Other, net | Amounts reclassified from AOCI    
Amounts reclassified from AOCI:    
Before tax 0 0
Tax effect 0 0
Amounts reclassified, net of tax 0 0
Total    
AOCI, Net of Tax [Roll Forward]    
AOCI, beginning balance (8,213) (12,506)
OCI before reclassifications, net of tax 907 (688)
Total OCI, net of tax 963 (716)
AOCI, ending balance (7,250) (13,222)
Total | Amounts reclassified from AOCI    
Amounts reclassified from AOCI:    
Before tax 73 (37)
Tax effect 17 (9)
Amounts reclassified, net of tax $ 56 $ (28)