Note 12 - Investments in Affiliates - Summarized Balance Sheet Information for Equity Method Investments (Details) - USD ($) $ in Thousands		Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Current assets		$ 1,593,276	$ 1,827,399	$ 1,566,433
Total assets		2,291,332	2,494,927	2,478,898
Current liabilities		994,246	1,069,318	1,048,286
Granite’s share of net assets		23,203	23,368	25,317
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Current assets		34,822	34,374	32,528
Noncurrent assets		75,679	78,829	68,929
Total assets		110,501	113,203	101,457
Current liabilities		21,182	23,685	18,794
Long-term liabilities	[1]	32,364	48,104	29,596
Total liabilities		53,546	71,789	48,390
Net assets		$ 56,955	$ 41,414	$ 53,067

[1] This balance is primarily related to local bank debt for equipment purchases and debt associated with our real estate investments.