Accumulated Other Comprehensive Income (Loss) - Amounts Reclassified Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other income (expense), net	$ (48.1)	$ (30.4)
Total reclassifications for the period	22.1	34.9
Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total reclassifications for the period	(19.0)
Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of postretirement plan items, before tax	23.4	35.9
Income tax benefit	(1.3)	(1.0)
Total reclassifications for the period	41.1
Amortization of prior service cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of postretirement plan items, before tax	(1.5)	(1.5)
Amortization of actuarial losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of postretirement plan items, before tax	43.9	37.4
Adjustment for substantial completion of liquidation of foreign subsidiaries | Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other income (expense), net	$ (19.0)	$ 0.0