Changes In Equity And Accumulated Other Comprehensive Loss (Classification Of Accumulated Other Comprehensive Income Reflected On Consolidated Balance Sheets) (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Changes In Equity And Comprehensive Income [Line Items]
Accumulated other comprehensive loss, beginning balance	$ (466.4)
Other comprehensive income (loss) before reclassifications	(52.7)
Amounts reclassified from accumulated other comprehensive income	15.3
Net current-period othre comprehensive income (loss)	(37.4)
Accumulated other comprehensive loss, ending balance	(503.8)
Deferred tax assets, other comprehensive loss	151.5	$ 148.2
Accumulated Defined Benefit Plans Adjustment
Changes In Equity And Comprehensive Income [Line Items]
Accumulated other comprehensive loss, beginning balance	(397.9)
Net current-period othre comprehensive income (loss)	15.3
Accumulated other comprehensive loss, ending balance	(382.6)
Accumulated Translation Adjustment
Changes In Equity And Comprehensive Income [Line Items]
Accumulated other comprehensive loss, beginning balance	(68.5)
Other comprehensive income (loss) before reclassifications	(52.7)
Net current-period othre comprehensive income (loss)	(52.7)
Accumulated other comprehensive loss, ending balance	$ (121.2)