Borrowings	3 Months Ended
Mar. 31, 2013
Debt Disclosure [Abstract]
Borrowings	5. Borrowings M&T had $1.2 billion of fixed and floating rate junior subordinated deferrable interest debentures (“Junior Subordinated Debentures”) outstanding at March 31, 2013 that are held by various trusts and were issued in connection with the issuance by those trusts of preferred capital securities (“Capital Securities”) and common securities (“Common Securities”). The proceeds from the issuances of the Capital Securities and the Common Securities were used by the trusts to purchase the Junior Subordinated Debentures. The Common Securities of each of those trusts are wholly owned by M&T and are the only class of each trust’s securities possessing general voting powers. The Capital Securities represent preferred undivided interests in the assets of the corresponding trust. Under the Federal Reserve Board’s current risk-based capital guidelines, the Capital Securities are includable in M&T’s Tier 1 capital. However, the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 that was signed into law on July 21, 2010 provides for a three-year phase-in related to the exclusion of trust preferred capital securities from Tier 1 capital for large financial institutions, including M&T. That phase-in period began on January 1, 2013. However, specific rules related to that phase-in period have not yet been finalized. Holders of the Capital Securities receive preferential cumulative cash distributions unless M&T exercises its right to extend the payment of interest on the Junior Subordinated Debentures as allowed by the terms of each such debenture, in which case payment of distributions on the respective Capital Securities will be deferred for comparable periods. During an extended interest period, M&T may not pay dividends or distributions on, or repurchase, redeem or acquire any shares of its capital stock. In the event of an extended interest period exceeding twenty quarterly periods for $350 million of Junior Subordinated Debentures due January 31, 2068, M&T must fund the payment of accrued and unpaid interest through an alternative payment mechanism, which requires M&T to issue common stock, non-cumulative perpetual preferred stock or warrants to purchase common stock until M&T has raised an amount of eligible proceeds at least equal to the aggregate amount of accrued and unpaid deferred interest on the Junior Subordinated Debentures due January 31, 2068. In general, the agreements governing the Capital Securities, in the aggregate, provide a full, irrevocable and unconditional guarantee by M&T of the payment of distributions on, the redemption of, and any liquidation distribution with respect to the Capital Securities. The obligations under such guarantee and the Capital Securities are subordinate and junior in right of payment to all senior indebtedness of M&T. The Capital Securities will remain outstanding until the Junior Subordinated Debentures are repaid at maturity, are redeemed prior to maturity or are distributed in liquidation to the Trusts. The Capital Securities are mandatorily redeemable in whole, but not in part, upon repayment at the stated maturity dates (ranging from 2027 to 2068) of the Junior Subordinated Debentures or the earlier redemption of the Junior Subordinated Debentures in whole upon the occurrence of one or more events set forth in the indentures relating to the Capital Securities, and in whole or in part at any time after an optional redemption prior to contractual maturity contemporaneously with the optional redemption of the related Junior Subordinated Debentures in whole or in part, subject to possible regulatory approval. During the first quarter of 2013, M&T Bank, the principal bank subsidiary of M&T, finalized a Bank Note Program whereby M&T Bank may offer up to $5 billion of unsecured senior and subordinated notes, which will mature 270 days or more from their date of issue. During March 2013, three-year floating rate senior notes due March 2016 were issued for $300 million and five-year 1.45% fixed rate senior notes due March 2018 were issued for $500 million. Also included in long-term borrowings are agreements to repurchase securities of $1.4 billion at each of March 31, 2013 and December 31, 2012. The agreements are subject to master netting arrangements and are fully collateralized.

5. Borrowings

M&T had $1.2 billion of fixed and floating rate junior subordinated deferrable interest debentures (“Junior Subordinated Debentures”) outstanding at March 31, 2013 that are held by various trusts and were issued in connection with the issuance by those trusts of preferred capital securities (“Capital Securities”) and common securities (“Common Securities”). The proceeds from the issuances of the Capital Securities and the Common Securities were used by the trusts to purchase the Junior Subordinated Debentures. The Common Securities of each of those trusts are wholly owned by M&T and are the only class of each trust’s securities possessing general voting powers. The Capital Securities represent preferred undivided interests in the assets of the corresponding trust.

Under the Federal Reserve Board’s current risk-based capital guidelines, the Capital Securities are includable in M&T’s Tier 1 capital. However, the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 that was signed into law on July 21, 2010 provides for a three-year phase-in related to the exclusion of trust preferred capital securities from Tier 1 capital for large financial institutions, including M&T. That phase-in period began on January 1, 2013. However, specific rules related to that phase-in period have not yet been finalized.

Holders of the Capital Securities receive preferential cumulative cash distributions unless M&T exercises its right to extend the payment of interest on the Junior Subordinated Debentures as allowed by the terms of each such debenture, in which case payment of distributions on the respective Capital Securities will be deferred for comparable periods. During an extended interest period, M&T may not pay dividends or distributions on, or repurchase, redeem or acquire any shares of its capital stock. In the event of an extended interest period exceeding twenty quarterly periods for $350 million of Junior Subordinated Debentures due January 31, 2068, M&T must fund the payment of accrued and unpaid interest through an alternative payment mechanism, which requires M&T to issue common stock, non-cumulative perpetual preferred stock or warrants to purchase common stock until M&T has raised an amount of eligible proceeds at least equal to the aggregate amount of accrued and unpaid deferred interest on the Junior Subordinated Debentures due January 31, 2068. In general, the agreements governing the Capital Securities, in the aggregate, provide a full, irrevocable and unconditional guarantee by M&T of the payment of distributions on, the redemption of, and any liquidation distribution with respect to the Capital Securities. The obligations under such guarantee and the Capital Securities are subordinate and junior in right of payment to all senior indebtedness of M&T.

The Capital Securities will remain outstanding until the Junior Subordinated Debentures are repaid at maturity, are redeemed prior to maturity or are distributed in liquidation to the Trusts. The Capital Securities are mandatorily redeemable in whole, but not in part, upon repayment at the stated maturity dates (ranging from 2027 to 2068) of the Junior Subordinated Debentures or the earlier redemption of the Junior Subordinated Debentures in whole upon the occurrence of one or more events set forth in the indentures relating to the Capital Securities, and in whole or in part at any time after an optional redemption prior to contractual maturity contemporaneously with the optional redemption of the related Junior Subordinated Debentures in whole or in part, subject to possible regulatory approval.

During the first quarter of 2013, M&T Bank, the principal bank subsidiary of M&T, finalized a Bank Note Program whereby M&T Bank may offer up to $5 billion of unsecured senior and subordinated notes, which will mature 270 days or more from their date of issue. During March 2013, three-year floating rate senior notes due March 2016 were issued for $300 million and five-year 1.45% fixed rate senior notes due March 2018 were issued for $500 million.

Also included in long-term borrowings are agreements to repurchase securities of $1.4 billion at each of March 31, 2013 and December 31, 2012. The agreements are subject to master netting arrangements and are fully collateralized.