Investment Securities - Pooled Trust Preferred Securities (Detail) (USD $) In Thousands, unless otherwise specified				9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Sep. 30, 2013 Pooled Trust Preferred Securities One [Member]	Sep. 30, 2013 Pooled Trust Preferred Securities One [Member] MM Community Funding IX [Member] Item	Sep. 30, 2013 Pooled Trust Preferred Securities One [Member] Reg Div Funding 2004 [Member] Item	Sep. 30, 2013 Pooled Trust Preferred Securities One [Member] Pretsl XII [Member] Item	Sep. 30, 2013 Pooled Trust Preferred Securities One [Member] Pretsl XXVII LTD [Member] Item	Sep. 30, 2013 Pooled Trust Preferred Securities One [Member] Trapeza Ser 13A [Member] Item	Sep. 30, 2013 Single Issuer Trust Preferred Securities [Member]	Sep. 30, 2013 Single Issuer Trust Preferred Securities [Member] First Empire Cap (M&T) [Member]	Sep. 30, 2013 Single Issuer Trust Preferred Securities [Member] First Empire Cap (M&T) [Member]	Sep. 30, 2013 Single Issuer Trust Preferred Securities [Member] Fleet Cap Tr V (BOA) [Member]	Sep. 30, 2013 Single Issuer Trust Preferred Securities [Member] JP Morgan Chase Cap XIII [Member]	Sep. 30, 2013 Single Issuer Trust Preferred Securities [Member] NB-Global [Member]	Sep. 30, 2013 Trust Preferred Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Pooled trust preferred securities, Class					B-2	B-2	B-1	B	A2A
Lowest Credit Rating					D	D	C	CCC	B+		BB+	BB+	Ba2	BBB	Ba2
Amortized Cost				$ 22,923	$ 2,067	$ 4,012	$ 2,670	$ 4,754	$ 9,420	$ 12,701	$ 958	$ 2,911	$ 3,371	$ 4,731	$ 730	$ 35,624
Available-for-sale securities, Fair Value	2,374,297	2,500,784	2,312,789	9,405	902	1,122	1,341	1,326	4,714	11,619	1,017	3,052	2,800	3,950	800	21,024
Available-for-sale, Unrealized Losses				(13,518)	(1,165)	(2,890)	(1,329)	(3,428)	(4,706)	(1,082)	59	141	(571)	(781)	70	(14,600)
Realized Losses 2013
# of Issuers Currently Performing					14	24	48	33	41
# of Issuers Currently Remaining					27	43	70	47	61
Actual Deferrals and Defaults as a Percent of Original Collateral					32.00%	39.90%	23.60%	25.10%	27.60%
Expected Defaults as a % of Remaining Performing Collateral					5.30%	6.00%	6.70%	4.60%	6.70%
Excess Subordination as a % of Current Performing Collateral					0.00%	0.00%	0.00%	34.60%	40.10%