Summary of Significant Accounting Policies Summary of Significant Accounting Policies, Revenue Recognition (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 820,035	$ 812,572	$ 1,623,000	$ 1,610,784
Gross profit	218,767	191,146	397,811	382,980
Costs of revenue	(601,268)	(621,426)	(1,225,189)	(1,227,804)
Corporate general and administrative expenses	(37,169)	(29,218)	(68,982)	(72,196)
Gains on divestitures and impairment charges, net	(737)	11,823	(5,282)	13,701
Operating income	182,335	150,105	334,111	297,083
Interest expense	(41,767)	(47,317)	(86,118)	(94,707)
Losses on early extinguishment of debt, net	11	7,579	150	7,579
Nonoperating Income (Expense)	1,166	874	(81)	1,594
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	141,723	96,083	247,762	196,391
Income Tax Expense (Benefit)	36,170	23,570	60,208	44,665
Net income	105,553	72,513	187,554	151,726
Net income attributable to noncontrolling interests	45	184	105	74
Net income attributable to common stockholders	$ 105,508	$ 72,329	$ 187,449	$ 151,652
Net income attributable to common stockholders, basic	$ 0.59	$ 0.40	$ 1.04	$ 0.83
Net income attributable to common stockholders, diluted	$ 0.59	$ 0.39	$ 1.03	$ 0.82
Change in amounts due for unfulfilled performance obligations			$ (18,151)	$ (3,770)
Financing Receivable, Allowance for Credit Loss, Noncurrent	$ (8,245)		(8,245)
Notes Receivable [Member] | Long Term [Member]
Financing Receivable, Allowance for Credit Loss, Noncurrent	$ (7,295)		$ (7,295)		$ (8,374)