Note 10 - Investments in Affiliates - Summarized Statement of Operations for Equity Method Investments (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue	$ 789,213	$ 1,008,910	$ 849,247	$ 653,886	$ 805,651	$ 1,062,129	$ 964,172	$ 669,913	$ 1,503,133	$ 2,512,043	$ 3,301,256	$ 3,501,865	$ 3,562,459
Range of increase in gross profit from each project, net	96,781	115,055	97,566	60,092	62,446	119,935	116,946	63,318	157,658	272,713	369,494	362,645	344,788
Increase to project profitability, net		57,488	28,246	(18,743)					9,503	66,991	91,817	22,127	(166,463)
Increase to net income/decrease to net loss	$ 19,176	65,198	19,578	(25,095)	$ (20,433)	$ 32,423	$ 55,747	$ (65,323)	(5,517)	59,681	78,857	2,414	(166,181)
Granite’s interest in affiliates’ net income		$ 3,491	$ 4,876	$ 1,289					$ 6,165	$ 9,656	13,571	12,586	8,783
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Revenue											377,256	302,084	194,717
Range of increase in gross profit from each project, net											95,816	74,939	48,948
Increase to project profitability, net											60,513	38,261	28,471
Increase to net income/decrease to net loss											$ 47,331	$ 33,864	$ 24,073