Derivative Financial Instruments - Amounts Related to Cash Flow Hedges (Details) - Interest Rate Contracts - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Cash Flow Hedges | Commercial loans
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Pre-tax gain (loss) recognized in OCI		$ 267	$ (129)	$ 736	$ (432)
Pre-tax gain (loss) reclassified from AOCI into expense		(92)	(79)	(185)	(134)
Fair value hedges | Net interest income
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Net income (expense) recognized		27	55	41	163
Fair value hedges | Net interest income | Investment securities
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Amounts related to interest settlements		70	115	141	278
Recognized on derivatives		(199)	185	(591)	627
Recognized on hedged items		210	(172)	611	(608)
Net income (expense) recognized	[1]	81	128	161	297
Fair value hedges | Net interest income | Long-term debt
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Amounts related to interest settlements		(18)	(51)	(40)	(90)
Recognized on derivatives		92	(63)	244	(295)
Recognized on hedged items		(128)	41	(323)	252
Net income (expense) recognized		(54)	(73)	(119)	(133)
Fair value hedges | Net interest income | Loans and leases
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Recognized on hedged items		$ 0	$ 0	$ (1)	$ (1)

[1] Includes $9 million and $18 million of income recognized for the three and six months ended June 30, 2025, respectively, and $10 million and $20 million for the three and six months ended June 30, 2024, respectively, from securities with terminated hedges that were reclassified to HTM. The income recognized was offset by the amortization of the fair value mark.