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Income Taxes - Additional Information (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Income Tax Contingency [Line Items]    
Increase in valuation allowance due to state net operating loss and tax credit carryforwards $ 0.3 $ 0.2
State net operating loss carryforwards 27.5  
State tax credit carryforwards 1.5  
Unrecognized tax benefits that would impact effective tax rate 2.8  
Reductions in the liability for unrecognized tax benefits due to expiration of statues of limitation 0.3  
Accrued interest expense 0.2 0.3
Liability for interest expense 0.3 0.3
Liability for penalties 0.3 $ 0.3
2003 through 2011 [Member] | Kansas [Member]    
Income Tax Contingency [Line Items]    
Audit settlement, net $ 0.1