Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ (1,213.7)	$ (1,244.1)	$ (1,299.6)	$ (1,326.5)
Other comprehensive income before reclassifications			(18.1)
Amounts reclassified from accumulated other comprehensive income	35.2	38.5	104.9	115.8
Current period other comprehensive income			86.8
Ending balance	(1,117.4)	(1,203.8)	(1,117.4)	(1,203.8)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4,010.9)	(3,765.2)	(4,084.8)	(3,815.8)
Ending balance	(3,998.0)	$ (3,942.9)	(3,998.0)	$ (3,942.9)
Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(896.7)
Other comprehensive income before reclassifications			(93.4)
Current period other comprehensive income			(93.4)
Ending balance	(990.1)		(990.1)
Postretirement Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(3,188.1)
Other comprehensive income before reclassifications			75.3
Amounts reclassified from accumulated other comprehensive income			104.9
Current period other comprehensive income			180.2
Ending balance	$ (3,007.9)		$ (3,007.9)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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