XML 63 R52.htm IDEA: XBRL DOCUMENT v3.10.0.1
Income Taxes - Additional Information (Detail) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2018
Dec. 31, 2017
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Mar. 31, 2018
Components Of Income Tax Expense Benefit [Line Items]            
Income tax effective rate 53.80%   45.30% 51.20% 76.40%  
Income tax expense (benefit) impact of the tax act $ (0.5) $ 8.3   $ (0.5)    
Minimum [Member]            
Components Of Income Tax Expense Benefit [Line Items]            
Decrease in unrecognized tax benefits           $ 2.1
Maximum [Member]            
Components Of Income Tax Expense Benefit [Line Items]            
Decrease in unrecognized tax benefits           $ 4.1