Quarterly report pursuant to Section 13 or 15(d)

Income Taxes - Additional Information (Detail)

v3.10.0.1
Income Taxes - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Income Tax Disclosure [Abstract]          
Effective income tax rate 11.30% 34.70% 22.70% 30.80%  
Federal statutory income tax rate     21.00% 35.00%  
Tax Cuts And Jobs Act Of 2017, Income tax expense (benefit) $ 0.1   $ 1.1   $ 1.0
Tax Cuts and Jobs Act of 2017, deferred tax asset, income tax expense (2.0)   5.0   7.0
Unrecognized tax benefits 25.2   25.2   25.2
Unrecognized Tax Benefits that Would Impact Effective Tax Rate 8.5   8.5   8.5
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued 2.2   2.2   2.1
Liability for Uncertainty in Income Taxes, Noncurrent $ 27.4   $ 27.4   $ 27.3