Restructuring and Other - Multi-Employer Pension Plan Charges - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Restructuring Cost And Reserve [Line Items]
Multi-employer pension plan charges	$ 0.5	$ 0.5	$ 1.7	$ 1.7
Accrued liabilities	390.5		390.5		$ 447.5
Other noncurrent liabilities	202.1		202.1		$ 180.2
Multi-employer pension plan withdrawal obligations
Restructuring Cost And Reserve [Line Items]
Accrued liabilities	5.1		5.1
Other noncurrent liabilities	$ 29.6		$ 29.6