Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosure [Abstract]
Income tax expense	$ 1,813,000	$ (2,468,000)	$ 7,056,000	$ 3,191,000
Effective tax rate			39.50%	13.00%
Increase in the effective tax			$ 5,500,000