Fair Value Disclosures (Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs) (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 14,798,000	$ 37,875,000	$ 14,094,000	$ 39,506,000
Included in earnings	0	0	0	(476,000)
Realized other-than-tempoary impairment	0	26,000	0	156,000
Principal paydowns	(143,000)	(1,826,000)	(378,000)	(5,143,000)
Included in other comprehensive income	(125,000)	1,212,000	814,000	3,244,000
Ending Balance	14,530,000	37,287,000	14,530,000	37,287,000
Other Equity Securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	2,803,000	2,820,000	2,797,000	3,156,000
Included in earnings	0	0	0	(97,000)
Realized other-than-tempoary impairment	0	0	0	0
Principal paydowns	0	0	0	0
Included in other comprehensive income	(34,000)	1,000	(28,000)	(238,000)
Ending Balance	2,769,000	2,821,000	2,769,000	2,821,000
Other Structured Financial Products [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	11,995,000	10,506,000	11,297,000	9,550,000
Included in earnings	0	0	0	0
Realized other-than-tempoary impairment	0	0	0	0
Principal paydowns	(143,000)	(37,000)	(378,000)	(114,000)
Included in other comprehensive income	(91,000)	975,000	842,000	2,008,000
Ending Balance	11,761,000	11,444,000	11,761,000	11,444,000
Non-Agency Residential Mortgage-Backed Securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	0	24,549,000	0	26,800,000
Included in earnings	0	0	0	(379,000)
Realized other-than-tempoary impairment	0	26,000	0	156,000
Principal paydowns	0	(1,789,000)	0	(5,029,000)
Included in other comprehensive income	0	236,000	0	1,474,000
Ending Balance	$ 0	$ 23,022,000	$ 0	$ 23,022,000