Age of Unrealized Losses and Fair Value of Related Securities (Detail) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Less than Twelve Months, Fair Value	$ 64,507,000	$ 97,569,000
Less than Twelve Months, Unrealized Losses	(1,980,000)	(7,563,000)
More than Twelve Months, Fair Value	71,851,000	79,948,000
More than Twelve Months, Unrealized Losses	(18,064,000)	(42,182,000)
Total,Fair Value	136,358,000	177,517,000
Total, Unrealized Losses	(20,044,000)	(49,745,000)
U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Less than Twelve Months, Fair Value	8,534,000	7,980,000
Less than Twelve Months, Unrealized Losses	(4,000)	(243,000)
More than Twelve Months, Fair Value	7,110,000
More than Twelve Months, Unrealized Losses	(32,000)
Total,Fair Value	15,644,000	7,980,000
Total, Unrealized Losses	(36,000)	(243,000)
Obligations of states and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Less than Twelve Months, Fair Value	10,660,000	141,000
Less than Twelve Months, Unrealized Losses	(529,000)	(1,000)
More than Twelve Months, Fair Value
More than Twelve Months, Unrealized Losses
Total,Fair Value	10,660,000	141,000
Total, Unrealized Losses	(529,000)	(1,000)
Residential mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Less than Twelve Months, Fair Value	43,368,000	41,673,000
Less than Twelve Months, Unrealized Losses	(901,000)	(1,655,000)
More than Twelve Months, Fair Value	21,967,000	22,639,000
More than Twelve Months, Unrealized Losses	(2,321,000)	(3,789,000)
Total,Fair Value	65,335,000	64,312,000
Total, Unrealized Losses	(3,222,000)	(5,444,000)
Trust preferred securities
Schedule of Available-for-sale Securities [Line Items]
Less than Twelve Months, Fair Value	1,173,000	23,962,000
Less than Twelve Months, Unrealized Losses	(506,000)	(1,061,000)
More than Twelve Months, Fair Value	27,669,000	44,758,000
More than Twelve Months, Unrealized Losses	(13,858,000)	(35,524,000)
Total,Fair Value	28,842,000	68,720,000
Total, Unrealized Losses	(14,364,000)	(36,585,000)
Corporate and other debt securities
Schedule of Available-for-sale Securities [Line Items]
Less than Twelve Months, Fair Value		3,243,000
Less than Twelve Months, Unrealized Losses		(173,000)
More than Twelve Months, Fair Value	2,491,000
More than Twelve Months, Unrealized Losses	(9,000)
Total,Fair Value	2,491,000	3,243,000
Total, Unrealized Losses	(9,000)	(173,000)
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Less than Twelve Months, Fair Value	772,000	20,570,000
Less than Twelve Months, Unrealized Losses	(40,000)	(4,430,000)
More than Twelve Months, Fair Value	12,614,000	12,551,000
More than Twelve Months, Unrealized Losses	(1,844,000)	(2,869,000)
Total,Fair Value	13,386,000	33,121,000
Total, Unrealized Losses	$ (1,884,000)	$ (7,299,000)