Investment Securities (Schedule Of Trust Preferred Securities - Pooled Issuers For OTTI Information) (Detail) (USD $) In Thousands, unless otherwise specified							12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Pooled Trust Preferred Securities [Member]		Dec. 31, 2011 Pooled Trust Preferred Securities [Member]		Dec. 31, 2012 Pooled Trust Preferred Securities [Member] Preferred Class B [Member] Security H [Member]		Dec. 31, 2012 Pooled Trust Preferred Securities [Member] Preferred Class B [Member] Security I [Member]		Dec. 31, 2012 Pooled Trust Preferred Securities [Member] Preferred Class B [Member] Security J [Member]		Dec. 31, 2012 Pooled Trust Preferred Securities [Member] Preferred Class B [Member] Security L [Member]		Dec. 31, 2012 Pooled Trust Preferred Securities [Member] Preferred Class A [Member] Security K [Member]		Dec. 31, 2012 Pooled Trust Preferred Securities [Member] Preferred Class A [Member] Security M [Member]		Dec. 31, 2012 Pooled Trust Preferred Securities [Member] Preferred Class A [Member] Security N [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	$ 3,069,182	$ 2,849,463	$ 46,018	[1],[2]	$ 52,606	[3]	$ 3,486	[2]	$ 4,467	[2]	$ 5,303	[2]	$ 8,725	[2]	$ 7,400	[2]	$ 7,191	[2]	$ 9,446	[2]
Gross Unrealized Losses	(31,489)	(51,186)	(19,811)	[1]	(23,608)	[3]	(1,649)		(2,110)		(2,719)		(4,240)		(3,474)		(4,141)		(1,478)
Fair Value			26,207				1,837		2,357		2,584		4,485		3,926		3,050		7,968
Lowest Credit Ratings							B	[4]	CCC	[4]	CCC	[4]	CCC	[4]	CCC	[4]	D	[4]	A	[4]
Total Other-Than-Temporary Impairment			$ (10,460)				$ (352)		$ (365)		$ (806)		$ (867)		$ (2,040)		$ (4,926)		$ (1,104)
% of Performing Bank/Insurance Issuers							92.00%		93.80%		92.00%		95.80%		68.60%		57.30%		92.00%
Current Deferrals/Defaults (As a % of Original Collateral)							7.20%		8.00%		9.90%		6.40%		34.30%		38.50%		9.90%

[1] Amortized cost is net of $10.5 million of credit related other-than-temporary impairment at December 31, 2012.

[2] For the securities previously deemed impaired, the amortized cost is reflective of previous OTTI recognized in earnings.

[3] Amortized cost is net of $10.5 million of credit related other-than-temporary impairment at December 31, 2011.

[4] The Company utilized credit ratings provided by Moody’s, S&P and Fitch in its evaluation of issuers.