Goodwill and Intangible Assets - Goodwill (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Beginning balance, Goodwill Gross Carrying Amount	$ 1,202.8	$ 731.3
Acquired goodwill, Gross Carrying Amount		474.0
Foreign currency translation, Gross Carrying Amount	9.0	(2.5)
Ending balance, Goodwill Gross Carrying Amount	1,211.8	1,202.8
Beginning balance, Accumulated Impairment Loss	(144.3)	(144.3)
Impairment of goodwill, Accumulated Impairment Loss	(1.1)
Ending balance, Accumulated Impairment Loss	(145.4)	(144.3)
Beginning balance, Goodwill Net	1,058.5	587.0
Acquired goodwill, Net		474.0
Impairment of goodwill, Net	(1.1)
Foreign currency translation, Net	9.0	(2.5)
Ending balance, Goodwill Net	$ 1,066.4	$ 1,058.5