Summary of Significant Accounting Policies Summary of Significant Accounting Policies, Revenue Recognition (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 918,241	$ 769,241	$ 2,541,241	$ 2,380,025
Gross profit	263,656	159,732	661,467	542,712
Costs of revenue	(654,585)	(609,509)	(1,879,774)	(1,837,313)
Corporate general and administrative expenses	(40,986)	(29,668)	(109,968)	(101,864)
Gains on divestitures and impairment charges, net	(543)	1,479	(5,825)	15,180
Operating income	223,213	128,585	557,324	425,668
Interest expense	(40,721)	(46,678)	(126,839)	(141,385)
Losses on early extinguishment of debt, net	18,278	9,058	18,428	16,637
Nonoperating Income (Expense)	629	20	548	1,614
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	164,843	72,869	412,605	269,260
Income Tax Expense (Benefit)	37,351	1,997	97,559	46,662
Net income	127,492	70,872	315,046	222,598
Net income attributable to noncontrolling interests	77	80	182	154
Net income attributable to common stockholders	$ 127,415	$ 70,792	$ 314,864	$ 222,444
Net income attributable to common stockholders, basic	$ 0.72	$ 0.39	$ 1.77	$ 1.22
Net income attributable to common stockholders, diluted	$ 0.72	$ 0.38	$ 1.74	$ 1.20
Change in amounts due for unfulfilled performance obligations			$ (42,300)	$ (3,849)
Financing Receivable, Allowance for Credit Loss, Noncurrent	$ (7,493)		(7,493)
Notes Receivable [Member] | Long Term [Member]
Financing Receivable, Allowance for Credit Loss, Noncurrent	$ (6,534)		$ (6,534)		$ (8,374)