Shareholders' Equity Changes in Accumulated Other Comprehensive Income (Loss) Balances (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2020	$ (72.5)	$ (108.0)	$ (58.4)	$ (72.7)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			4.7
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	7.1	10.5	(8.5)	(14.6)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(9.8)
Balance as of June 30, 2021	(63.5)	$ (99.6)	(63.5)	$ (99.6)
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2020			(39.1)
Balance as of June 30, 2021	(47.6)		(47.6)
Cash Flow Hedging | Foreign currency contracts
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2020			(15.5)
Reclassification to the statement of income			4.5
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(1.3)
Balance as of June 30, 2021	(12.3)		(12.3)
Retirement Plan and Other Activity
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2020			(3.8)
Reclassification to the statement of income			0.2
Balance as of June 30, 2021	$ (3.6)		$ (3.6)