Shareholders Equity (Details) (USD $)	3 Months Ended	6 Months Ended												6 Months Ended				6 Months Ended
	Jun. 30, 2011	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 Series A Fixed Rate Cumulative Perpetual Preferred Stock [Member]	Dec. 31, 2010 Series A Fixed Rate Cumulative Perpetual Preferred Stock [Member]	Jun. 30, 2011 Series B Mandatory Convertible Non-cumulative Preferred Stock [Member]	Dec. 31, 2010 Series B Mandatory Convertible Non-cumulative Preferred Stock [Member]	Jun. 30, 2011 Series C Fixed Rate Cumulative Perpetual Preferred Stock [Member]	Dec. 31, 2010 Series C Fixed Rate Cumulative Perpetual Preferred Stock [Member]	Jun. 30, 2011 Series D Fixed Rate Non Cumulative Perpetual Preferred Stock [Member]	Dec. 31, 2010 Series D Fixed Rate Non Cumulative Perpetual Preferred Stock [Member]	Jun. 30, 2011 Ten Year Warrant Series A Preferred [Member]	Jun. 30, 2011 Ten Year Warrant Series C Preferred [Member]	Jun. 30, 2011 Series A [Member]	Jun. 30, 2011 Series B [Member]	Mar. 31, 2011 Series B [Member]	Jun. 30, 2011 Series C [Member]	Jun. 30, 2011 Series D [Member]	Jun. 30, 2011 Preferred series A and C first five years [Member]	Jun. 30, 2011 Preferred series A and C after five years [Member]
Issued and outstanding preferred stock
Preferred stock, shares issued	381,500	381,500	778,000	230,000		0		151,500		50,000
Preferred stock, shares outstanding	50,000	50,000	0	230,000		0		151,500		50,000
Carrying value	$ 860,901,000	$ 860,901,000	$ 740,657,000	$ 223,037,000	$ 578,630,000	$ 0	$ 26,500,000	$ 137,864,000	$ 135,527,000	$ 500,000,000	$ 0
Shareholders Equity (Textuals) [Abstract]
Preferred stock, shares authorized	1,000,000	1,000,000	1,000,000	230,000	600,000	26,500		151,500		50,000
Preferred stock, par value	$ 1.00	$ 1.00	$ 1.00
Liquidation preference	$ 1,000	$ 1,000	$ 1,000	$ 1,000		$ 1,000		$ 1,000		$ 10,000
Ten-year warrant to purchase common stock												1,218,522	407,542
Exercise price of each class of warrants or rights outstanding														$ 73.86			$ 55.76
Preferred stock dividend rate															10% per year			6.875% per year	5% per year	9% per year
Number of shares of M&T common stock resulting from conversion of Series B Preferred																433,144
Preferred stock, shares redeemed														370,000
Accelerated amortization of preferred stock discount as per redemption														$ 11,200,000
Limitation by U.S. Treasury on maximum amount of dividend to be paid per common stock quarterly	0.70 per share
Redemption days of shares by Company		90 days