Income Taxes (Adjustment to Significant Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Deferred Tax Assets
Timing of expense recognition		$ 36,055	$ 23,580
Net operating losses		10,140	5,478
Other, net		33,507	29,342
Deferred tax assets		79,702	58,400
Valuation Allowance		(460)	(460)
Net deferred tax assets		79,242	57,940
Deferred Tax Liabilities
Intangible assets, due primarily to purchase accounting		(34,679)	(37,157)
Fixed assets, due primarily to purchase accounting		(107,081)	(100,516)
Construction contract accounting		(12,564)	(9,197)
Joint ventures - construction		(29,609)	(29,949)
Other		(24,970)	(3,943)
Deferred tax liabilities		(208,903)	(180,762)
Net deferred tax liability		(129,661)	(122,822)
Total current assets		2,837,756	2,608,939
Other assets		45,235	47,290
Total assets		4,038,620	3,861,300
Accrued expenses and other current liabilities		107,925	134,127
Total current liabilities		1,518,943	1,448,819
Total liabilities		2,485,597	2,441,073
Total liabilities and stockholders' equity		4,038,620	3,861,300
Net Deferred Tax Liability
Long-term deferred tax asset		1,346
Long-term deferred tax liability		(131,007)	(122,822)
Net deferred tax liability		$ (129,661)	(122,822)
As Previously Reported [Member]
Deferred Tax Assets
Timing of expense recognition			58,048
Net operating losses			3,564
Other, net			114,225
Deferred tax assets			175,837
Valuation Allowance			(460)
Net deferred tax assets			175,377
Deferred Tax Liabilities
Intangible assets, due primarily to purchase accounting			(99,549)
Fixed assets, due primarily to purchase accounting			(101,022)
Construction contract accounting			(7,530)
Joint ventures - construction			(27,604)
Other			(62,494)
Deferred tax liabilities			(298,199)
Net deferred tax liability			(122,822)
Total current assets			2,635,245
Other assets			202,125
Total assets			4,042,441
Accrued expenses and other current liabilities			(159,016)
Total current liabilities			(1,473,708)
Total liabilities			(2,622,214)
Total liabilities and stockholders' equity			(4,042,441)
Net Deferred Tax Liability
Current deferred tax asset			26,306
Long-term deferred tax asset			149,071
Current deferred tax liability			(24,889)
Long-term deferred tax liability			(273,310)
Net deferred tax liability			(122,822)
Adjustments [Member]
Deferred Tax Assets
Timing of expense recognition			(34,468)
Net operating losses			1,914
Other, net			(84,883)
Deferred tax assets			(117,437)
Net deferred tax assets			(117,437)
Deferred Tax Liabilities
Intangible assets, due primarily to purchase accounting			62,392
Fixed assets, due primarily to purchase accounting			506
Construction contract accounting			(1,667)
Joint ventures - construction			(2,345)
Other			58,551
Deferred tax liabilities			117,437
Total current assets			(24,889)
Other assets			(149,071)
Total assets			(173,960)
Accrued expenses and other current liabilities			24,889
Total current liabilities			24,889
Total liabilities			173,960
Total liabilities and stockholders' equity			173,960
Net Deferred Tax Liability
Current deferred tax asset			(24,889)
Long-term deferred tax asset			(149,071)
Current deferred tax liability			24,889
Long-term deferred tax liability			149,071
As Restated [Member]
Deferred Tax Assets
Timing of expense recognition			23,580
Net operating losses			5,478
Other, net			29,342
Deferred tax assets			58,400
Valuation Allowance			(460)
Net deferred tax assets			57,940
Deferred Tax Liabilities
Intangible assets, due primarily to purchase accounting			(37,157)
Fixed assets, due primarily to purchase accounting			(100,516)
Construction contract accounting			(9,197)
Joint ventures - construction			(29,949)
Other			(3,943)
Deferred tax liabilities			(180,762)
Net deferred tax liability	[1]		(122,822)
Total current assets	[1]		2,610,356
Other assets	[1]		53,054
Total assets	[1]		3,868,481
Accrued expenses and other current liabilities	[1]		(134,127)
Total current liabilities	[1]		(1,448,819)
Total liabilities	[1]		(2,448,254)
Total liabilities and stockholders' equity	[1]		(3,868,481)
Net Deferred Tax Liability
Current deferred tax asset	[1]		1,417
Long-term deferred tax liability	[1]		(124,239)
Net deferred tax liability	[1]		$ (122,822)

[1] The amounts reflected are prior to the Company's adoption of ASU 2015-03 (see discussion in Note 1) and ASU 2015-17, discussed below.