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Income Taxes - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Income Tax [Line Items]      
Federal statutory income tax rate 35.00%    
Interest related to unrecognized tax benefits $ 0.2 $ 0.3 $ 0.1
Accrued interest and penalties related to unrecognized tax benefits 1.0 1.3  
Unrecognized tax benefits that would affect the Company's effective tax rate if recognized 1.2 1.2  
Cash (received) paid for income taxes 16.4 20.8 $ 20.6
Tax credit recognized in fourth quarter of each year $ 1.0 $ 1.0  
Maximum [Member]      
Income Tax [Line Items]      
Income tax year open for examination 2015    
Maximum [Member] | State and Local Jurisdiction [Member]      
Income Tax [Line Items]      
Income tax year open for examination 2015    
Minimum [Member]      
Income Tax [Line Items]      
Income tax year open for examination 2013    
Minimum [Member] | State and Local Jurisdiction [Member]      
Income Tax [Line Items]      
Income tax year open for examination 2006