Goodwill and Other Intangible Assets - Goodwill and Accumulated Goodwill Impairment Losses (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($)
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	$ 2,510,173
Accumulated goodwill impairment losses, beginning balance	(1,281,751)
Goodwill, net, beginning balance	1,228,422
Goodwill acquired during year	101,171
Other	24,534
Goodwill, gross, ending balance	2,635,878
Accumulated goodwill impairment losses, ending balance	(1,281,751)
Goodwill, net, ending balance	1,354,127
Operating segments | Northeast segment
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	848,424
Accumulated goodwill impairment losses, beginning balance	(707,593)
Goodwill, net, beginning balance	140,831
Goodwill acquired during year	61,714
Other	(800)
Goodwill, gross, ending balance	909,338
Accumulated goodwill impairment losses, ending balance	(707,593)
Goodwill, net, ending balance	201,745
Operating segments | South segment
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	185,158
Accumulated goodwill impairment losses, beginning balance	(34,522)
Goodwill, net, beginning balance	150,636
Goodwill acquired during year	39,457
Other	9,000
Goodwill, gross, ending balance	233,615
Accumulated goodwill impairment losses, ending balance	(34,522)
Goodwill, net, ending balance	199,093
Operating segments | West segment
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	210,423
Accumulated goodwill impairment losses, beginning balance	(16,633)
Goodwill, net, beginning balance	193,790
Goodwill acquired during year	0
Other	8,134
Goodwill, gross, ending balance	218,557
Accumulated goodwill impairment losses, ending balance	(16,633)
Goodwill, net, ending balance	201,924
Operating segments | Midwest segment
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	1,110,052
Accumulated goodwill impairment losses, beginning balance	(435,283)
Goodwill, net, beginning balance	674,769
Goodwill acquired during year	0
Other	8,200
Goodwill, gross, ending balance	1,118,252
Accumulated goodwill impairment losses, ending balance	(435,283)
Goodwill, net, ending balance	682,969
Other
Goodwill [Roll Forward]
Goodwill, gross, beginning balance	156,116
Accumulated goodwill impairment losses, beginning balance	(87,720)
Goodwill, net, beginning balance	68,396
Goodwill acquired during year	0
Other	0
Goodwill, gross, ending balance	156,116
Accumulated goodwill impairment losses, ending balance	(87,720)
Goodwill, net, ending balance	$ 68,396