Gross Unrealized Losses and Fair Value by Length of Time of Available-For-Sale Securities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012 OptionPlan	Dec. 31, 2011 OptionPlan
Available-for-Sale Securities
Schedule of Available-for-sale Securities [Line Items]
Number of securities	7	6
Fair Value	$ 46,404	$ 11,271
Less than 12 months	231	37
More than 12 months	236	480
Total Unrealized Losses	467	517
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Number of securities	13	1
State and municipal | Available-for-Sale Securities
Schedule of Available-for-sale Securities [Line Items]
Number of securities	1	1
Fair Value	390	397
Less than 12 months	1	2
More than 12 months	0	0
Total Unrealized Losses	1	2
Mortgage-Backed | Available-for-Sale Securities
Schedule of Available-for-sale Securities [Line Items]
Number of securities	2	3
Fair Value	12,653	5,081
Less than 12 months	128	13
More than 12 months	0	0
Total Unrealized Losses	128	13
Corporate Debt | Available-for-Sale Securities
Schedule of Available-for-sale Securities [Line Items]
Number of securities	1	1
Fair Value	1,996	3,326
Less than 12 months	4	22
More than 12 months	0	0
Total Unrealized Losses	4	22
U.S. Government Agencies | Available-for-Sale Securities
Schedule of Available-for-sale Securities [Line Items]
Number of securities	2
Fair Value	29,900
Less than 12 months	98
More than 12 months	0
Total Unrealized Losses	98
Trust Preferred | Available-for-Sale Securities
Schedule of Available-for-sale Securities [Line Items]
Number of securities	1	1
Fair Value	1,465	2,467
Less than 12 months	0	0
More than 12 months	236	480
Total Unrealized Losses	$ 236	$ 480