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Income Taxes - Additional Information (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Income Tax Disclosure [Abstract]      
Federal statutory rate 35.00% 35.00% 35.00%
Annual effective income tax rate, percentage 29.00% 28.00% 27.00%
Net deferred tax asset $ 36,360 $ 49,654  
Alternative minimum tax credit carryforward $ 5,065 $ 8,627