Components of Income Tax Expense Benefit (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Components Of Income Tax Expense Benefit [Line Items]
Current	$ 850,000	$ 588,000	$ 2,052,000	$ 1,572,000
Deferred			$ 42,000	$ (193,000)