Borrowings - Schedule of Borrowings (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Short-term borrowings
Federal funds purchased and repurchase agreements	$ 264	$ 316
FHLB advances	4,500	5,000
Total short-term borrowings	4,764	5,316
Long-term borrowings
Senior notes	3,743	3,741
FHLB advances	2,005	5
Subordinated notes	867	873
Asset-backed notes	822	474
Other	10	10
Total long-term borrowings	11,319	8,201
M&T
Long-term borrowings
Senior notes	3,256	2,482
Subordinated notes	75	76
Junior subordinated debentures — M&T	$ 541	$ 540

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Amount after offset of short term borrowing where a bank borrows, at the federal funds rate, from another bank and securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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Including both current and noncurrent portions, Federal Home Loan Bank borrowings initially due beyond one year or beyond the normal operating cycle if longer.

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Amount of advance from Federal Home Loan Bank (FHLBank) maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Including the current and noncurrent portions, carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Junior Subordinated Notes, which have a lower priority than senior instruments.

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Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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Carrying amount of collateralized debt obligations with maturities initially due after one year or beyond the operating cycle, if longer, excluding the current portion. Obligations include, but not limited to, mortgage loans, chattel loans, and other borrowings secured by assets.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

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