Components of Income Tax Expense Benefit (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Components Of Income Tax Expense Benefit [Line Items]
Current	$ 732,000	$ 565,000	$ 1,202,000	$ 984,000
Deferred			$ 42,000