Accumulated Other Comprehensive Income (Loss) - After-Tax Components of and Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 2,775.5	$ 2,427.8	$ 2,180.0
Amounts classified into accumulated other comprehensive (loss) income	32.3	12.3	(19.0)
Amounts reclassified into earnings	(1.8)	5.2	22.0
Net current period other comprehensive (loss) income	30.5	17.5	(5.6)
Ending Balance	3,064.8	2,775.5	2,427.8
Revision of Prior Period, Accounting Standards Update, Adjustment [Member] | ASU 2018-02 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Adoption of ASU 2018-02			(8.6)
Foreign Currency Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	7.2	(11.5)	(25.3)
Amounts classified into accumulated other comprehensive (loss) income	(3.9)	18.7	13.8
Net current period other comprehensive (loss) income	(3.9)	18.7	13.8
Ending Balance	3.3	7.2	(11.5)
Derivative Hedging Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	4.2	5.5	4.2
Amounts classified into accumulated other comprehensive (loss) income	1.1	(3.7)	5.1
Amounts reclassified into earnings	(2.4)	2.4	(3.8)
Net current period other comprehensive (loss) income	(1.3)	(1.3)	1.3
Ending Balance	2.9	4.2	5.5
Defined Benefit Plan Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(66.5)	(66.6)	(45.9)
Amounts classified into accumulated other comprehensive (loss) income	35.1	(2.7)	(37.9)
Amounts reclassified into earnings	0.6	2.8	25.8
Net current period other comprehensive (loss) income	35.7	0.1	(20.7)
Ending Balance	(30.8)	(66.5)	(66.6)
Defined Benefit Plan Adjustments [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment [Member] | ASU 2018-02 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Adoption of ASU 2018-02			(8.6)
Accumulated Other Comprehensive (Loss) Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(55.1)	(72.6)	(67.0)
Ending Balance	$ (24.6)	$ (55.1)	$ (72.6)