Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ (1,228.3)	$ (1,299.6)
Other comprehensive income (loss) before reclassifications	(16.2)
Amounts reclassified from accumulated other comprehensive income	22.1	34.9
Current period other comprehensive income	5.9
Ending balance	(209.4)	(1,282.5)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4,088.6)	(4,084.8)
Ending balance	(4,082.7)	$ (4,048.4)
Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(872.9)
Other comprehensive income (loss) before reclassifications	(62.6)
Amounts reclassified from accumulated other comprehensive income	(19.0)
Current period other comprehensive income	(81.6)
Ending balance	(954.5)
Postretirement Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(3,215.7)
Other comprehensive income (loss) before reclassifications	46.4
Amounts reclassified from accumulated other comprehensive income	41.1
Current period other comprehensive income	87.5
Ending balance	$ (3,128.2)