Goodwill and Other Intangible Assets - Goodwill and Accumulated Goodwill Impairment Losses (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	$ 2,510.2
Accumulated goodwill impairment losses, beginning balance	(1,281.8)
Goodwill, net, beginning balance	1,228.4
Goodwill acquired during year	103.3
Other	18.7
Goodwill, gross, ending balance	2,632.2
Accumulated goodwill impairment losses, ending balance	(1,281.8)
Goodwill, net, ending balance	1,350.4
Operating segments | Northeast segment
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	848.4
Accumulated goodwill impairment losses, beginning balance	(707.6)
Goodwill, net, beginning balance	140.8
Goodwill acquired during year	62.8
Other	(1.5)
Goodwill, gross, ending balance	909.7
Accumulated goodwill impairment losses, ending balance	(707.6)
Goodwill, net, ending balance	202.1
Operating segments | South segment
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	185.2
Accumulated goodwill impairment losses, beginning balance	(34.6)
Goodwill, net, beginning balance	150.6
Goodwill acquired during year	40.5
Other	7.2
Goodwill, gross, ending balance	232.9
Accumulated goodwill impairment losses, ending balance	(34.6)
Goodwill, net, ending balance	198.3
Operating segments | West segment
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	210.4
Accumulated goodwill impairment losses, beginning balance	(16.6)
Goodwill, net, beginning balance	193.8
Goodwill acquired during year	0.0
Other	6.4
Goodwill, gross, ending balance	216.8
Accumulated goodwill impairment losses, ending balance	(16.6)
Goodwill, net, ending balance	200.2
Operating segments | Midwest segment
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	1,110.1
Accumulated goodwill impairment losses, beginning balance	(435.3)
Goodwill, net, beginning balance	674.8
Goodwill acquired during year	0.0
Other	6.6
Goodwill, gross, ending balance	1,116.7
Accumulated goodwill impairment losses, ending balance	(435.3)
Goodwill, net, ending balance	681.4
Other
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	156.1
Accumulated goodwill impairment losses, beginning balance	(87.7)
Goodwill, net, beginning balance	68.4
Goodwill acquired during year	0.0
Other	0.0
Goodwill, gross, ending balance	156.1
Accumulated goodwill impairment losses, ending balance	(87.7)
Goodwill, net, ending balance	$ 68.4