Fair Value Disclosures (Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs) (Detail) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013		Jun. 30, 2014	Jun. 30, 2013
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 14,235,000	$ 38,726,000		$ 14,094,000	$ 39,506,000
Other-than-temporary impairment		(97,000)	[1]		(485,000)	[1]
Included in other comprehensive income (before taxes)	563,000	(754,000)		704,000	(1,146,000)
Ending Balance	14,798,000	37,875,000		14,798,000	37,875,000
Other Equity Securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	2,816,000	3,157,000		2,797,000	3,156,000
Other-than-temporary impairment		(97,000)	[1]		(97,000)	[1]
Included in other comprehensive income (before taxes)	(13,000)	(240,000)		6,000	(239,000)
Ending Balance	2,803,000	2,820,000		2,803,000	2,820,000
Other Structured Financial Products [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	11,419,000	9,977,000		11,297,000	9,550,000
Other-than-temporary impairment		0	[1]		0	[1]
Included in other comprehensive income (before taxes)	576,000	529,000		698,000	956,000
Ending Balance	11,995,000	10,506,000		11,995,000	10,506,000
Non-Agency Residential Mortgage-Backed Securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	0	25,592,000		0	26,800,000
Other-than-temporary impairment		0	[1]		(388,000)	[1]
Included in other comprehensive income (before taxes)	0	(1,043,000)		0	(1,863,000)
Ending Balance	$ 0	$ 24,549,000		$ 0	$ 24,549,000

[1] Included in noninterest income, net impairment losses recognized in earnings.