Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Accrued amount for interest and penalties related to the non-payment of U.S. federal income taxes	$ 99,000	$ 164,000	$ 289,000	$ 202,000
Amount of valuation allowance on deferred tax assets					10,700,000
Benefit for income taxes		1,200,000		1,200,000
Income tax liability		600,000		600,000
Unrecognized tax benefits	$ 0		$ 0