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Derivatives - Gains/(Losses) on Derivatives Associated with Cash Flow Hedges and Mortgage Banking Hedges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) expected to be reclassified to earnings in the next twelve months	$ (24)	$ (24)	$ (24)	$ (24)
Hedging Instruments And Hedged Items
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses), cash flow hedges			(26)	(45)
Gain (loss) reclassified from AOCI into interest income			24	2
Hedging Instruments And Hedged Items \| Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses), cash flow hedges			(13)	69
Cash Flow Hedge \| Hedging Instruments And Hedged Items
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses), cash flow hedges	(59)	(25)
Gain (loss) reclassified from AOCI into interest income	13	3
Cash Flow Hedge \| Hedging Instruments And Hedged Items \| Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses), cash flow hedges	(66)	37
Mortgage Banking Hedges \| Hedging Instruments And Hedged Items \| Option contracts written
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	0	(2)	2	1
Mortgage Banking Hedges \| Hedging Instruments And Hedged Items \| Forward contracts written
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	$ (2)	$ 9	$ 6	$ 27