Goodwill and Other Intangible Assets - Goodwill and Accumulated Goodwill Impairment Losses (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	$ 2,639.9
Accumulated goodwill impairment losses, beginning balance	(1,482.8)
Goodwill, net, beginning balance	1,157.1
Goodwill acquired during the period	18.0
Goodwill, gross, ending balance	2,657.9
Accumulated goodwill impairment losses, ending balance	(1,482.8)
Goodwill, net, ending balance	1,175.1
Operating Segments | Northeast
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	914.3
Accumulated goodwill impairment losses, beginning balance	(761.4)
Goodwill, net, beginning balance	152.9
Goodwill acquired during the period	9.2
Goodwill, gross, ending balance	923.5
Accumulated goodwill impairment losses, ending balance	(761.4)
Goodwill, net, ending balance	162.1
Operating Segments | South
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	236.6
Accumulated goodwill impairment losses, beginning balance	(61.0)
Goodwill, net, beginning balance	175.6
Goodwill acquired during the period	0.0
Goodwill, gross, ending balance	236.6
Accumulated goodwill impairment losses, ending balance	(61.0)
Goodwill, net, ending balance	175.6
Operating Segments | West
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	216.8
Accumulated goodwill impairment losses, beginning balance	(16.6)
Goodwill, net, beginning balance	200.2
Goodwill acquired during the period	0.0
Goodwill, gross, ending balance	216.8
Accumulated goodwill impairment losses, ending balance	(16.6)
Goodwill, net, ending balance	200.2
Operating Segments | Midwest
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	1,116.7
Accumulated goodwill impairment losses, beginning balance	(556.1)
Goodwill, net, beginning balance	560.6
Goodwill acquired during the period	0.0
Goodwill, gross, ending balance	1,116.7
Accumulated goodwill impairment losses, ending balance	(556.1)
Goodwill, net, ending balance	560.6
Other
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	155.5
Accumulated goodwill impairment losses, beginning balance	(87.7)
Goodwill, net, beginning balance	67.8
Goodwill acquired during the period	8.8
Goodwill, gross, ending balance	164.3
Accumulated goodwill impairment losses, ending balance	(87.7)
Goodwill, net, ending balance	$ 76.6