Benefit Plans - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum year of service to qualify for post-retirement medical benefits	20 years
Minimum age to qualify for post-retirement medical benefits	60 years
Condition to qualify for post-retirement medical benefits	Employees who worked 20 years and attained a minimum age of 60 by September 1, 2000
Accumulated benefit obligation	$ 1,600,000	$ 1,400,000
Estimated net gain for the postretirement plan	86,000
Prior service costs for the postretirement plan	77,000
Weighted-average annual assumed rate of increase in the per capita cost of coverage benefits, 2014	3.40%
Weighted-average annual assumed rate of increase in the per capita cost of coverage benefits, 2016	6.00%	4.75%
Weighted-average annual assumed rate of increase in the per capita cost of coverage benefits, 2017	5.75%	4.50%
Weighted-average annual assumed rate of increase in the per capita cost of coverage benefits, 2018	5.50%
Weighted-average annual assumed rate of increase in the per capita cost of coverage benefits, 2019	5.25%
Weighted-average annual assumed rate of increase in the per capita cost of coverage benefits, 2020	5.00%
Weighted-average annual assumed rate of increase in the per capita cost of coverage benefits, 2021	4.50%
Weighted-average annual assumed rate of increase in the per capita cost of coverage benefits, 2013		3.00%
Weighted-average annual assumed rate of increase in the per capita cost of coverage benefits, 2015		5.00%
Weighted-average annual assumed rate of increase in the per capita cost of coverage benefits, 2012	6.00%
Weighted-average annual assumed rate of decrease in the per capita cost of coverage benefits, 2017	4.50%
Matching contribution percentage	25.00%	25.00%	25.00%
Maximum pre-tax contribution of the employees' base pay	6.00%	6.00%	6.00%
Percentage of vesting of participants in Home Savings contributions	100.00%
Minimum service required for vesting in Home Savings contribution	3 years
Expense related to the plan	224,000	204,000	230,000
Number of shares allocated to plan participants	0	0
Shares, Granted	7,124
Options granted in 2009 exercisable period	3 years
Weighted average period to cost recognized	2 years
Weighted average remaining life for outstanding stock	4 years 11 months 27 days
Exercise price range, lower range limit	$ 1.20
Exercise price range, upper range limit	$ 5.89
Maximum amount deduction of employees salary under employee stock purchase plan	900
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognition of stock option expense	25,000	24,000	18,000
Unrecognized cost of nonvested stock options granted	21,000
Expected additional expense for 2016	5,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognition of stock option expense	482,000	328,000	725,000
Unrecognized cost of nonvested stock options granted	400,000
Expected additional expense for 2016	299,000
Non Vested shares issued during 2014	223,624	192,937
Vested shares during 2015	97,804
Vested shares during 2016	60,606
Vested shares during 2017	65,214
Expected additional expense for 2017	86,000
2007 Long-Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares of stock, option plan, maximum	2,000,000
Shares, Granted	7,124	17,787
Maximum term for option exercisable	10 years
Unrecognized cost of nonvested stock options granted	26,000
1999 Long-Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares of stock, option plan, maximum	3,569,766
Option expiry term (Years)	10 years
Executive Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognition of stock option expense	926,000	448,000
Percentage of amount paid in cash	80.00%
Percentage of amount paid in restricted stock	20.00%
Restricted stock vesting period	3 years
Long Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognition of stock option expense	$ 179,000	$ 0