Retirement Plans - Amounts Recognized in Other Comprehensive Income (Loss) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Amortization of Net actuarial loss	$ 26.1
Amortization of Net prior service credit	0.0
Amounts arising during the period, Net actuarial loss	(102.5)
Amounts arising during the period, Net prior service credit	0.0
Amounts arising during the period, Divestiture	1.6
Amounts arising during the period, Curtailment	0.0
Amounts arising during the period, Settlements	98.4
Amounts arising during the period, Foreign currency loss	(0.8)
Total	22.8
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Amortization of Net actuarial loss	0.1
Amortization of Net prior service credit	(12.7)
Amounts arising during the period, Net actuarial loss	(4.8)
Amounts arising during the period, Net prior service credit	33.8
Amounts arising during the period, Divestiture	0.0
Amounts arising during the period, Curtailment	(19.5)
Amounts arising during the period, Settlements	0.0
Amounts arising during the period, Foreign currency loss	(0.4)
Total	$ (3.5)