Retirement Plans - Amounts Recognized on Consolidated Balance Sheets (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit cost (included in accrued liabilities)	$ (447.5)	$ (541.7)
Pension liabilities	(102.7)	(119.4)
Other postretirement benefits plan liabilities	(113.2)	(134.1)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Prepaid pension cost (included in other noncurrent assets)	39.9	22.8
Accrued benefit cost (included in accrued liabilities)	(2.7)	(2.7)
Pension liabilities	(102.7)	(119.4)
Other postretirement benefits plan liabilities	0.0	0.0
Net liabilities recognized in the Consolidated Balance Sheets - Continuing Operations	(65.5)	(99.3)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Prepaid pension cost (included in other noncurrent assets)	0.0	0.0
Accrued benefit cost (included in accrued liabilities)	(0.6)	(0.6)
Pension liabilities	0.0	0.0
Other postretirement benefits plan liabilities	(113.2)	(134.1)
Net liabilities recognized in the Consolidated Balance Sheets - Continuing Operations	$ (113.8)	$ (134.7)