Goodwill and Other Intangible Assets - Changes in Goodwill (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Line Items]
Balance at beginning of period	$ 2,414.0	$ 2,396.8
Acquisitions	1,080.4	17.3
Divestitures		(0.1)
Balance at end of period	3,494.4	2,414.0
East Group
Goodwill [Line Items]
Balance at beginning of period	572.5	574.3
Acquisitions	186.9
Goodwill reclassified from/(allocated to) assets held for sale		0.1
Transfer of operations from East Group to West Group		(1.9)
Balance at end of period	759.4	572.5
West Group
Goodwill [Line Items]
Balance at beginning of period	1,841.5	1,822.5
Acquisitions	893.5	17.3
Goodwill reclassified from/(allocated to) assets held for sale		(0.1)
Divestitures		(0.1)
Transfer of operations from East Group to West Group		1.9
Balance at end of period	$ 2,735.0	$ 1,841.5