Employee Benefit Plans - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Employee Benefit Plans [Line Items]
Defined contribution plan employee compensation eligible for employer contribution, maximum	50.00%
Defined contribution plan employer matching contribution	6.00%
Expenses relating to 401(k) contributions to employees	$ 89	$ 91
Shares held by the Employee stock ownership plan and allocated to participants	87,505	87,505
Employee stock ownership plan, vesting period	7 years
Employee stock ownership plan, cash contributions	57	58
Employee stock ownership plan , compensation expense	61	53
Former Chief Executive Officer
Employee Benefit Plans [Line Items]
Deferred compensation plan payable period	15 years
Deferred compensation plan payment accrued	921	764
Deferred compensation plan expense	$ 157	$ 150
Maximum
Employee Benefit Plans [Line Items]
Defined contribution plan employee compensation eligible for employer contribution, maximum	15.00%