Income Taxes - Schedule of Income Tax Expense (Parenthetical) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Components Of Income Tax Expense Benefit [Line Items]
Deferred state income taxes	$ 1,934,000	$ 2,280,000	$ 1,963,000