Income Tax Expense (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule Of Income Tax Expense Benefit [Line Items]
Total Current	$ 9,919,000	$ 3,124,000	$ 12,151,000
Total Deferred	(1,337,000)	6,015,000	(70,000)
Total Income Tax Expense	8,582,000	9,139,000	12,081,000
Federal
Schedule Of Income Tax Expense Benefit [Line Items]
Total Current	9,787,000	2,347,000	9,688,000
Total Deferred	(1,210,000)	5,446,000	(62,000)
State
Schedule Of Income Tax Expense Benefit [Line Items]
Total Current	132,000	777,000	2,463,000
Total Deferred	$ (127,000)	$ 569,000	$ (8,000)