Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Line Items]
Operating loss carryforwards	$ 41,000,000
Net operating loss carryforwards, beginning of expiration	2021
Recognized interest income, net of Federal income tax expense	56,000	0	124,000
Accrued interest receivable, net of Federal Income tax benefits	$ 0	$ 2,700,000