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Income Taxes - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Sep. 30, 2014
Sep. 30, 2013
Dec. 31, 2013
Income Tax Disclosure [Abstract]          
Unrecognized tax benefits $ 3.0   $ 3.0   $ 6.2
Expected change in unrecognized tax benefits $ 2.5   $ 2.5    
Estimated effective tax rates 35.90% 41.30% 35.80% 34.00%  
Federal statutory rate   35.00%   35.00%