Retirement Plans and Deferred Compensation - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Costs incurred under defined contribution pension plan	$ 653,000	$ 884,000	$ 1,315,000
Amount charged to expenses in connection with agreements for supplemental benefits plans	399,000	423,000	428,000
Aggregate death benefit of life insurance policies	493,000	546,000
Corresponding cash surrender value of Policies	299,000	304,000
Net expenses recorded in connection with life insurance policies	$ 4,000	$ 11,000	$ 17,000
Minimum [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Discount rates for supplemental retirement benefits plans	6.00%
Maximum [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Discount rates for supplemental retirement benefits plans	12.00%