Summary of Significant Accounting Policies Revenue Recognition Impact (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		4 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 778,786	$ 731,346	$ 10,400	$ 2,369,360	$ 2,282,298
Costs and expenses:	(612,616)	(581,570)		(1,819,301)	(1,771,765)
Gross Profit	166,170	149,776		550,059	510,533
General and administrative expenses	(41,070)	(38,992)		(106,990)	(121,644)
Gains on divestitures and impairment charges, net	7,970	(143)		15,317	5,545
Unusual or Infrequent Item, or Both, 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	$ 1,100	254,322	299,452
Net (income) loss attributable to noncontrolling interests	(58)	23		(160)	(105)
Net Income (Loss) Attributable to Parent	$ 68,935	$ 56,164		$ 254,162	$ 299,347
Basic	$ 0.38	$ 0.30		$ 1.39	$ 1.59
Net income attributable to common stockholders, diluted	$ 0.37	$ 0.29		$ 1.36	$ 1.56
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 106			$ 1,124
Costs and expenses:	(253)			(14,205)
Gross Profit	(147)			(13,081)
General and administrative expenses				0
Gains on divestitures and impairment charges, net	0			0
Unusual or Infrequent Item, or Both, Net of Insurance Proceeds	0			0
Operating income	(147)			(13,081)
Interest expense				0
Loss on early extinguishment of debt, net	0			0
Other income (expense), net	0			0
Income before income taxes	(147)			(13,081)
(Provision for) benefit from income taxes	42			2,538
Net income	(105)			(10,543)
Net (income) loss attributable to noncontrolling interests	0			0
Net Income (Loss) Attributable to Parent	$ (105)			$ (10,543)
Basic	$ (0.58)			$ (57.66)
Net income attributable to common stockholders, diluted	$ (0.57)			$ (56.22)
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 778,892			$ 2,370,484
Costs and expenses:	(612,869)			(1,833,506)
Gross Profit	166,023			536,978
General and administrative expenses	(41,070)			(106,990)
Gains on divestitures and impairment charges, net	7,970			15,317
Unusual or Infrequent Item, or Both, Net of Insurance Proceeds	(767)			(437)
Operating income	132,156			444,868
Interest expense	(46,419)			(134,514)
Loss on early extinguishment of debt, net	0			(10,131)
Other income (expense), net	152			2,416
Income before income taxes	85,889			302,639
(Provision for) benefit from income taxes	(17,001)			(58,860)
Net income	68,888			243,779
Net (income) loss attributable to noncontrolling interests	(58)			(160)
Net Income (Loss) Attributable to Parent	$ 68,830			$ 243,619
Basic	$ 380.57			$ 1,332.28
Net income attributable to common stockholders, diluted	$ 371.13			$ 1,299.18