Note 11 - Construction Joint Ventures - Schedule of Unconsolidated Construction Joint Ventures Revenue and Costs (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Cost of revenue		$ 612,128	$ 580,675
Collaborative Arrangement [Member]
Revenue		83,702	110,516
Cost of revenue		95,717	131,058
Granite’s interest in gross loss		(12,015)	(20,542)
Collaborative Arrangement [Member] | Corporate Joint Venture [Member]
Revenue		62,030	415,934
Cost of revenue		228,460	411,485
Collaborative Arrangement [Member] | Co-venturer [Member] | Other Partners Interest in Partnerships [Member]
Revenue	[1]	(21,672)	305,418
Cost of revenue	[1]	$ 132,743	$ 280,427

[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 and estimates primarily related to contract forecast differences.