Borrowed Funds - Breakdown of Borrowed Funds (Details) - USD ($)	Sep. 30, 2024	Dec. 31, 2023
Debt Instrument
Federal Home Loan Bank and Federal Reserve Bank advances	$ 19,250,000,000	$ 20,250,000,000
Total wholesale borrowings	19,310,000,000	20,250,000,000
Junior subordinated debentures	581,000,000	579,000,000
Subordinated notes	442,000,000	438,000,000
Total borrowed funds	20,333,000,000	21,267,000,000
Total wholesale borrowings
Debt Instrument
Total wholesale borrowings	19,310,000,000	20,250,000,000
FHLB advances
Debt Instrument
Federal Home Loan Bank and Federal Reserve Bank advances	18,250,000,000	19,250,000,000
Federal Reserve Bank term funding
Debt Instrument
Fed funds purchased	1,000,000,000.0	1,000,000,000
Total borrowed funds	0
Repurchase agreements
Debt Instrument
Fed funds purchased	60,000,000	0
Junior subordinated debentures
Debt Instrument
Junior subordinated debentures	581,000,000	579,000,000
Subordinated notes
Debt Instrument
Subordinated notes	$ 442,000,000	$ 438,000,000

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