Derivative Instruments and Hedging Activities - Effects of Fair Value and Cash Flow Hedge Accounting (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Interest income:
Investment Securities	$ 850	$ 784	$ 1,682	$ 1,554
Loans, Including Loans Held for Sale	14,911	12,449	29,646	22,606
Other	624	595	1,288	1,086
Interest-bearing Deposits	(3,338)	(3,120)	(6,725)	(5,835)
Securitized Debt Obligations	(117)	(164)	(258)	(340)
Senior and Subordinated Notes	(535)	(535)	(1,067)	(1,040)
Non-interest income (expense)	412	361	725	616
Amortization expense (benefit)	(20)	(16)	(40)	(26)
Income Statement Location [Axis]: us-gaap:NoninterestIncomeOther
Interest income:
Realized gain (loss) on foreign exchange contracts reclassified from AOCI	(1)	(20)	75	(146)
Fair value hedges \| Income Statement Location [Axis]: us-gaap:InterestAndDividendIncomeSecurities
Interest income:
Net income (expense) recognized on fair value hedges	0	12	1	26
Fair value hedges \| Income Statement Location [Axis]: us-gaap:InterestAndFeeIncomeLoansAndLeases
Interest income:
Net income (expense) recognized on fair value hedges	0	0	0	0
Fair value hedges \| Income Statement Location [Axis]: us-gaap:InterestBearingDepositLiabilities
Interest income:
Net income (expense) recognized on fair value hedges				(65)
Fair value hedges \| Income Statement Location [Axis]: us-gaap:InterestBearingDepositsInBanks
Interest income:
Net income (expense) recognized on fair value hedges	(7)	(30)	(16)
Fair value hedges \| Income Statement Location [Axis]: us-gaap:NoninterestIncomeOther
Interest income:
Net income (expense) recognized on fair value hedges	0	0	0	0
Fair value hedges \| Income Statement Location [Axis]: us-gaap:OtherInterestAndDividendIncome
Interest income:
Net income (expense) recognized on fair value hedges	0	0	0	0
Fair value hedges \| Income Statement Location [Axis]: us-gaap:SecuredDebt
Interest income:
Net income (expense) recognized on fair value hedges	(22)	(36)	(43)	(86)
Fair value hedges \| Income Statement Location [Axis]: us-gaap:UnsecuredDebt
Interest income:
Net income (expense) recognized on fair value hedges	(48)	(115)	(96)	(235)
Fair value hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:InterestAndDividendIncomeSecurities
Interest income:
Interest recognized on derivatives	3	22	7	54
Gains (losses) recognized on derivatives	102	(62)	159	(160)
Gains (losses) recognized on hedged items	(105)	52	(165)	132
Excluded component of fair value hedges	0	0	0	0
Fair value hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:InterestAndFeeIncomeLoansAndLeases
Interest income:
Interest recognized on derivatives	0	0	0	0
Gains (losses) recognized on derivatives	0	0	0	0
Gains (losses) recognized on hedged items	0	0	0	0
Excluded component of fair value hedges	0	0	0	0
Fair value hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:InterestBearingDepositLiabilities
Interest income:
Interest recognized on derivatives				(65)
Gains (losses) recognized on derivatives				115
Gains (losses) recognized on hedged items				(115)
Excluded component of fair value hedges				0
Fair value hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:InterestBearingDepositsInBanks
Interest income:
Interest recognized on derivatives	(7)	(30)	(16)
Gains (losses) recognized on derivatives	(13)	40	(32)
Gains (losses) recognized on hedged items	13	(40)	32
Excluded component of fair value hedges	0	0	0
Fair value hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:NoninterestIncomeOther
Interest income:
Interest recognized on derivatives	0	0	0	0
Gains (losses) recognized on derivatives	(6)	49	(16)	72
Gains (losses) recognized on hedged items	6	(49)	16	(72)
Excluded component of fair value hedges	0	0	0	0
Fair value hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:OtherInterestAndDividendIncome
Interest income:
Interest recognized on derivatives	0	0	0	0
Gains (losses) recognized on derivatives	0	0	0	0
Gains (losses) recognized on hedged items	0	0	0	0
Excluded component of fair value hedges	0	0	0	0
Fair value hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:SecuredDebt
Interest income:
Interest recognized on derivatives	(22)	(37)	(43)	(86)
Gains (losses) recognized on derivatives	(23)	44	(36)	117
Gains (losses) recognized on hedged items	23	(43)	36	(117)
Excluded component of fair value hedges	0	0	0	0
Fair value hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:UnsecuredDebt
Interest income:
Interest recognized on derivatives	(70)	(146)	(141)	(294)
Gains (losses) recognized on derivatives	(259)	309	(380)	784
Gains (losses) recognized on hedged items	282	(277)	426	(724)
Excluded component of fair value hedges	(1)	(1)	(1)	(1)
Cash flow hedges \| Income Statement Location [Axis]: us-gaap:InterestAndDividendIncomeSecurities
Interest income:
Net income (expense) recognized on cash flow hedges	(2)	(1)	(4)	0
Cash flow hedges \| Income Statement Location [Axis]: us-gaap:InterestAndFeeIncomeLoansAndLeases
Interest income:
Net income (expense) recognized on cash flow hedges	(158)	(237)	(335)	(478)
Cash flow hedges \| Income Statement Location [Axis]: us-gaap:InterestBearingDepositLiabilities
Interest income:
Net income (expense) recognized on cash flow hedges				0
Cash flow hedges \| Income Statement Location [Axis]: us-gaap:InterestBearingDepositsInBanks
Interest income:
Net income (expense) recognized on cash flow hedges	0	0	0
Cash flow hedges \| Income Statement Location [Axis]: us-gaap:NoninterestIncomeOther
Interest income:
Net income (expense) recognized on cash flow hedges	0	2	0	1
Cash flow hedges \| Income Statement Location [Axis]: us-gaap:OtherInterestAndDividendIncome
Interest income:
Net income (expense) recognized on cash flow hedges	2	3	5	5
Cash flow hedges \| Income Statement Location [Axis]: us-gaap:SecuredDebt
Interest income:
Net income (expense) recognized on cash flow hedges	0	0	0	0
Cash flow hedges \| Income Statement Location [Axis]: us-gaap:UnsecuredDebt
Interest income:
Net income (expense) recognized on cash flow hedges	0	0	0	0
Cash flow hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:InterestAndDividendIncomeSecurities
Interest income:
Realized gains (losses) reclassified from AOCI into net income	(2)	(1)	(4)	0
Cash flow hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:InterestAndFeeIncomeLoansAndLeases
Interest income:
Realized gains (losses) reclassified from AOCI into net income	(158)	(237)	(335)	(478)
Cash flow hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:InterestBearingDepositLiabilities
Interest income:
Realized gains (losses) reclassified from AOCI into net income				0
Cash flow hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:InterestBearingDepositsInBanks
Interest income:
Realized gains (losses) reclassified from AOCI into net income	0	0	0
Cash flow hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:NoninterestIncomeOther
Interest income:
Realized gains (losses) reclassified from AOCI into net income	0	0	0	0
Cash flow hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:OtherInterestAndDividendIncome
Interest income:
Realized gains (losses) reclassified from AOCI into net income	0	0	0	0
Cash flow hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:SecuredDebt
Interest income:
Realized gains (losses) reclassified from AOCI into net income	0	0	0	0
Cash flow hedges \| Interest rate contracts: \| Income Statement Location [Axis]: us-gaap:UnsecuredDebt
Interest income:
Realized gains (losses) reclassified from AOCI into net income	0	0	0	0
Cash flow hedges \| Foreign exchange and other contracts \| Income Statement Location [Axis]: us-gaap:InterestAndDividendIncomeSecurities
Interest income:
Realized gains (losses) reclassified from AOCI into net income	0	0	0	0
Cash flow hedges \| Foreign exchange and other contracts \| Income Statement Location [Axis]: us-gaap:InterestAndFeeIncomeLoansAndLeases
Interest income:
Realized gains (losses) reclassified from AOCI into net income	0	0	0	0
Cash flow hedges \| Foreign exchange and other contracts \| Income Statement Location [Axis]: us-gaap:InterestBearingDepositLiabilities
Interest income:
Realized gains (losses) reclassified from AOCI into net income				0
Cash flow hedges \| Foreign exchange and other contracts \| Income Statement Location [Axis]: us-gaap:InterestBearingDepositsInBanks
Interest income:
Realized gains (losses) reclassified from AOCI into net income	0	0	0
Cash flow hedges \| Foreign exchange and other contracts \| Income Statement Location [Axis]: us-gaap:NoninterestIncomeOther
Interest income:
Realized gains (losses) reclassified from AOCI into net income	0	2	0	1
Cash flow hedges \| Foreign exchange and other contracts \| Income Statement Location [Axis]: us-gaap:OtherInterestAndDividendIncome
Interest income:
Realized gains (losses) reclassified from AOCI into net income	2	3	5	5
Cash flow hedges \| Foreign exchange and other contracts \| Income Statement Location [Axis]: us-gaap:SecuredDebt
Interest income:
Realized gains (losses) reclassified from AOCI into net income	0	0	0	0
Cash flow hedges \| Foreign exchange and other contracts \| Income Statement Location [Axis]: us-gaap:UnsecuredDebt
Interest income:
Realized gains (losses) reclassified from AOCI into net income	$ 0	$ 0	$ 0	$ 0

Amortization of Basis Adjustment on Discontinued Hedges

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Realized Gains (Losses) On Foreign Exchange Contracts Reclassified From AOCI

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Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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Net gain (loss) relating to components of the gain (loss) on the fair value hedging instrument excluded from the assessment of fair value hedge effectiveness. Recognized in earnings.

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Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period.

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