Income Taxes (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)
Net Deferred Tax Liability
Deferred tax asset	1,346
Deferred tax liability	(131,007)	(122,822)
Net deferred tax liability	$ (129,661)	$ (122,822)