Related Party Transactions (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Related Party Transaction [Line Items]
Payments for life insurance policies			$ 284,000	$ 283,000
Related Customer [Member] | Management [Member]
Related Party Transaction [Line Items]
Charges to related party	123,000	128,000	382,000	345,000
Related party receivables	843,000		843,000		860,000
Related party revenues	318,000	331,000	924,000	938,000
Accounts receivable, related party	1,100,000		1,100,000		775,000
Deferred Compensation, Excluding Share-based Payments and Retirement Benefits [Member] | Management [Member]
Related Party Transaction [Line Items]
Estimated fair value of life insurance policies	8,700,000		8,700,000		7,900,000
Deferred Compensation, Excluding Share-based Payments and Retirement Benefits [Member] | Board of Directors Chairman [Member]
Related Party Transaction [Line Items]
Payments for life insurance policies	0	0	284,000	283,000
Deferred Compensation, Excluding Share-based Payments and Retirement Benefits [Member] | Chief Executive Officer [Member]
Related Party Transaction [Line Items]
Payments for life insurance policies	$ 0	$ 0	$ 0	$ 0