Note 10 - Investments in Affiliates - Summarized Statement of Operations for Equity Method Investments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue	$ 683,196	$ 925,854	$ 834,671	$ 566,332	$ 830,390	$ 955,761	$ 811,866	$ 530,862	$ 3,010,053	$ 3,128,879	$ 2,914,877
Gross profit	51,652	101,960	98,232	53,712	93,319	113,015	81,048	17,271	305,556	304,653	189,785
Income before taxes									(9,496)	8,145	(40,224)
Net income	$ (20,433)	$ 32,423	$ 55,747	$ (65,323)	$ 5,687	$ (98,357)	$ (973)	$ (72,538)	2,414	(166,181)	(56,702)
Granite’s interest in affiliates’ net income									3,465	5,191	6,991
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Revenue									57,838	49,707	70,439
Gross profit									16,944	21,563	23,418
Income before taxes									11,584	15,653	20,761
Net income									11,584	15,653	20,761
Granite’s interest in affiliates’ net income									$ 3,465	$ 5,191	$ 6,991