Unaudited Condensed Consolidated Statement of Operations Statement - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Product Information [Line Items]
Revenues	$ 778,786	$ 731,346	$ 2,369,360	$ 2,282,298
Costs and expenses:	(612,616)	(581,570)	$ (1,819,301)	(1,771,765)
Document Period End Date			Sep. 30, 2018
Operating profit	166,170	149,776	$ 550,059	510,533
General and administrative expenses	(41,070)	(38,992)	(106,990)	(121,644)
Gains (losses) on divestitures and impairment charges, net	(7,970)	143	(15,317)	(5,545)
Hurricane Expenses, Net of Insurance Proceeds	(767)	(1,290)	(437)	(1,290)
Operating income	132,303	109,351	457,949	393,144
Interest expense	(46,419)	(42,754)	(134,514)	(125,473)
Loss on early extinguishment of debt, net	0	0	(10,131)	0
Other income (expense), net	152	(19)	2,416	(1,049)
Income before income taxes	86,036	66,578	315,720	266,622
(Provision for) benefit from income taxes	(17,043)	(10,437)	(61,398)	32,830
Net Income	68,993	56,141	254,322	299,452
Net (income) loss attributable to noncontrolling interests	(58)	23	(160)	(105)
Net income attributable to common stockholders	$ 68,935	$ 56,164	$ 254,162	$ 299,347
Basic earnings per share:
Net income attributable to common stockholders, basic	$ 0.38	$ 0.30	$ 1.39	$ 1.59
Basic weighted average number of shares	180,858	187,435	182,859	187,761
Diluted earnings per share:
Net income attributable to common stockholders, diluted	$ 0.37	$ 0.29	$ 1.36	$ 1.56
Diluted weighted average number of shares	185,460	192,243	187,517	192,417
Dividends declared per share	$ 0.17	$ 0.15	$ 0.51	$ 0.43
Product [Member]
Product Information [Line Items]
Revenues	$ 392,410	$ 363,934	$ 1,158,224	$ 1,116,551
Costs and expenses:	(203,349)	(189,818)	(600,997)	(588,370)
Service [Member]
Product Information [Line Items]
Revenues	323,246	319,810	1,035,794	1,012,631
Costs and expenses:	(188,893)	(179,924)	(568,034)	(546,978)
Product and Service, Other [Member]
Product Information [Line Items]
Revenues	63,130	47,602	175,342	153,116
Costs and expenses:	$ (220,374)	$ (211,828)	$ (650,270)	$ (636,417)