Investment Securities - Pooled Trust Preferred Securities (Detail) (USD $) In Thousands, unless otherwise specified				6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Jun. 30, 2014 Pooled Trust Preferred Securities One [Member]	Jun. 30, 2014 Pooled Trust Preferred Securities One [Member] Reg Div Funding 2004 [Member] Item	Jun. 30, 2014 Pooled Trust Preferred Securities One [Member] Pretsl XII [Member] Item	Jun. 30, 2014 Pooled Trust Preferred Securities One [Member] Trapeza Ser 13A [Member] Item	Jun. 30, 2014 Single Issuer Trust Preferred Securities [Member]	Jun. 30, 2014 Single Issuer Trust Preferred Securities [Member] First Empire Cap (M&T) [Member]	Jun. 30, 2014 Single Issuer Trust Preferred Securities [Member] First Empire Cap (M&T) [Member]	Jun. 30, 2014 Single Issuer Trust Preferred Securities [Member] Fleet Cap Tr V (BOA) [Member]	Jun. 30, 2014 Single Issuer Trust Preferred Securities [Member] J P Morgan Chase Cap XIII [Member]	Jun. 30, 2014 Single Issuer Trust Preferred Securities [Member] NB-Global [Member]	Jun. 30, 2014 Single Issuer Trust Preferred Securities [Member] Chase Capital [Member]	Jun. 30, 2014 Trust Preferred Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Pooled trust preferred securities, Class					B-2	B	A2A
Lowest Credit Rating					D	Caa3	B+		BB+	BB+	BB+	BBB	BB+	BBB
Amortized Cost				$ 18,041	$ 4,012	$ 4,596	$ 9,433	$ 13,519	$ 960	$ 2,914	$ 3,377	$ 4,739	$ 743	$ 786	$ 31,560
Available-for-sale securities, Fair Value	2,536,057	2,372,201	2,659,084	6,422	223	1,701	4,498	13,081	1,018	3,053	2,975	4,325	850	860	19,503
Available-for-sale, Unrealized Losses				(11,619)	(3,789)	(2,895)	(4,935)	(438)	58	139	(402)	(414)	107	74	(12,057)
Realized Losses 2014
# of Issuers Currently Performing					24	35	46
# of Issuers Currently Remaining					42	47	61
Actual Deferrals and Defaults as a Percent of Original Collateral					37.60%	20.50%	22.00%
Expected Defaults as a % of Remaining Performing Collateral					8.10%	5.70%	0.40%
Excess Subordination as a % of Current Performing Collateral					0.00%	39.40%	54.70%