v3.26.1
Shareholders' Equity and Accumulated Other Comprehensive Income (Loss) (Schedule of Accumulated Other Comprehensive Income) (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Dec. 31, 2024
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]        
Pre-tax AOCI activity, Period Start $ (2,057) $ (3,912)    
Tax Effect, period start 522 984    
Unrealized losses on securities transferred to held to maturity during the period, tax 0 (38)    
Unrealized losses on securities transferred from available for sale during the period 0 (115)    
Reclassification adjustments for amortization on unrealized losses on securities transferred to held for maturity, tax 6 7    
Reclassification adjustments for amortization on unrealized losses on securities transferred to held for maturity, after Tax (18) (15)    
Other Comprehensive Income (Loss), before Tax (245) 850    
Other Comprehensive Income (Loss), Tax 62 (214)    
Other comprehensive income, net of tax (183) 636    
Stockholders Equity Other Tax   0    
Stockholders Equity Other After Tax   9    
Stockholders Equity Other Before Tax   9    
OCIDebtSecuritiesAvailableForSaleUnrealizedGainLossTransferredToHeldToMaturityBeforeAdjustmentTax 0 (38)    
Unrealized losses on securities transferred to held to maturity during the period 0 115    
Unrealized holding gains (losses) on available for sale securities, tax 39 (113)    
Unrealized holding gains (losses) arising during the period on securities available for sale, net of tax (116) 345    
Reclassification adjustments for securities gains (losses) realized in net income, tax 1 6    
Reclassification adjustments for securities gains (losses) realized in net income (net of tax) (2) (19)    
Unrealized holding gains (losses) on derivatives arising during the period (118) 203    
Net change in unrealized gains (losses) on derivative instruments, net of tax (91) 253    
Reclassification adjustments for amortization of actuarial (gains) losses and settlements realized in net income (net of tax) (4) (4)    
Pre-tax AOCI activity, Period End (2,302) (3,053)    
Tax Effect, period end 584 770    
Net actuarial gains and losses arising during the period, tax 0 0    
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start (1,535) (2,928)    
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End (1,718) (2,283)    
Unrealized losses on securities transferred to held to maturity:        
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]        
Pre-tax AOCI activity, Period Start (867) (744)    
Tax Effect, period start 219 188    
OCIDebtSecuritiesAvailableForSaleTransferToHeldToMaturityUnrealizedGainLossBeforeAdjustmentBeforeTax   (153)    
Unrealized losses on securities transferred to held to maturity during the period, tax   38    
Unrealized losses on securities transferred from available for sale during the period   (115)    
Reclassification adjustments for amortization on unrealized losses on securities transferred to held for maturity, before Tax 24 22    
Reclassification adjustments for amortization on unrealized losses on securities transferred to held for maturity, tax (6) (7)    
Reclassification adjustments for amortization on unrealized losses on securities transferred to held for maturity, after Tax 18 15    
Other Comprehensive Income (Loss), before Tax   (131)    
Other Comprehensive Income (Loss), Tax   31    
Other comprehensive income, net of tax   (100)    
AOCI component, net of tax (630) (656) $ (648) $ (556)
Pre-tax AOCI activity, Period End (843) (875)    
Tax Effect, period end 213 219    
Unrealized gains (losses) on securities available for sale:        
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]        
Pre-tax AOCI activity, Period Start (574) (1,958)    
Tax Effect, period start 146 490    
Other Comprehensive Income (Loss), before Tax (152) 636    
Other Comprehensive Income (Loss), Tax 38 (157)    
Other comprehensive income, net of tax (114) 479    
AOCI component, net of tax (542) (989) (428) (1,468)
OCIDebtSecuritiesAvailableForSaleUnrealizedGainLossTransferredToHeldToMaturityArisingDuringBeforeTax   153    
OCIDebtSecuritiesAvailableForSaleUnrealizedGainLossTransferredToHeldToMaturityBeforeAdjustmentTax   38    
Unrealized losses on securities transferred to held to maturity during the period   115    
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment and Tax (155) 458    
Unrealized holding gains (losses) on available for sale securities, tax 39 (113)    
Unrealized holding gains (losses) arising during the period on securities available for sale, net of tax (116) 345    
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax 3 25    
Reclassification adjustments for securities gains (losses) realized in net income, tax (1) (6)    
Reclassification adjustments for securities gains (losses) realized in net income (net of tax) 2 19    
Pre-tax AOCI activity, Period End (726) (1,322)    
Tax Effect, period end 184 333    
Unrealized gains (losses) on derivative instruments designated as cash flow hedges:        
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]        
Pre-tax AOCI activity, Period Start (91) (662)    
Tax Effect, period start 23 168    
Other Comprehensive Income (Loss), before Tax (122) 339    
Other Comprehensive Income (Loss), Tax 31 (86)    
Other comprehensive income, net of tax (91) 253    
AOCI component, net of tax (159) (241) (68) (494)
OCI, before Reclassifications, before Tax, Attributable to Parent (158) 272    
OCI, before reclassifications, tax, attributable to parent 40 (69)    
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent (36) (67)    
Reclassification from AOCI, Current Period, Tax 9 (17)    
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent 27 50    
Pre-tax AOCI activity, Period End (213) (323)    
Tax Effect, period end 54 82    
Defined benefit pension plans and other post employment benefit plans:        
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]        
Pre-tax AOCI activity, Period Start (525) (548)    
Tax Effect, period start 134 138    
AOCI component, net of tax (387) (406) $ (391) $ (410)
Reclassification adjustments for amortization of actuarial (gains) losses and settlements realized in net income, before Tax 5 (6)    
Reclassification adjustments for amortization of actuarial (gains) losses and settlements realized in net income, Tax (1) (2)    
Reclassification adjustments for amortization of actuarial (gains) losses and settlements realized in net income (net of tax) 4 (4)    
Pre-tax AOCI activity, Period End (520) (542)    
Tax Effect, period end $ 133 $ 136