Investments in Affiliates Equity Method Investment Summarized Income Statement Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Granite’s interest in affiliates’ net income	$ 7,177	$ 3,210	$ 901
Other Affiliates [Member] | Joint Venture Unconsolidated [Member]
Revenue	56,127	47,457	46,597
Gross profit	22,398	19,117	10,315
Income (loss) before taxes	19,117	8,446	3,647
Net income (loss)	19,117	8,446	3,647
Granite’s interest in affiliates’ net income	$ 7,177	$ 3,210	$ 901