Construction and Line Item Joint Ventures Schedule of Unconsolidated Construction Joint Ventures Revenue and Costs (Details) - Unconsolidated Construction Joint Venture [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Joint Venture Unconsolidated [Member]
Unconsolidated Joint Venture [Line Items]
Revenue		$ 2,057,336	$ 1,958,158	$ 1,924,544
Cost of Revenue		1,995,915	1,915,376	1,819,257
Other Partners Interest in Joint Venture [Member]
Unconsolidated Joint Venture [Line Items]
Revenue	[1]	1,469,550	1,387,532	1,341,334
Cost of Revenue	[1]	1,394,347	1,360,459	1,279,954
Reporting Entitys Interest in Joint Venture [Member]
Unconsolidated Joint Venture [Line Items]
Revenue		587,786	570,626	583,210
Cost of Revenue		601,568	554,917	539,303
Gross Profit (Loss)		$ (13,782)	$ 15,709	$ 43,907

[1] Partners’ interest and adjustments includes amounts to reconcile total revenue and total cost of revenue as reported by our partners to Granite’s interest adjusted to reflect our accounting policies primarily related to gross profit forecast differences.