Stockholders' Equity - Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	$ 829.5
Balance at end of period	880.0
Marketable Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	1.7	$ 1.8
Balance at end of period	1.7	1.8
Currency Translation
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(72.2)	(67.4)
Other comprehensive income (loss)	4.2	1.3
Balance at end of period	(68.0)	(66.1)
Accumulated Defined Benefit Plans Adjustment | Defined Benefit Pension Plans
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(120.9)	(154.1)
Other comprehensive income (loss)	1.8	2.5
Balance at end of period	(119.1)	(151.6)
Accumulated Defined Benefit Plans Adjustment | OPEB
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	0.1	0.3
Other comprehensive income (loss)	(0.1)	(0.2)
Balance at end of period		0.1
Total Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(191.3)	(219.4)
Other comprehensive income (loss)	5.9	3.6
Balance at end of period	$ (185.4)	$ (215.8)