Note 11 - Investments in Affiliates - Summarized Balance Sheet Information for Equity Method Investments (Details) - USD ($) $ in Thousands		Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Current assets		$ 1,566,434	$ 1,455,246	$ 1,423,942
Total assets		2,478,898	2,379,996	2,508,654
Current liabilities		1,048,285	943,256	889,600
Granite’s share of net assets		75,625	75,287	74,511
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Current assets		155,442	133,882	122,608
Noncurrent assets		160,598	164,620	163,790
Total assets		316,040	298,502	286,398
Current liabilities		71,267	52,583	54,044
Long-term liabilities	[1]	57,911	66,108	60,714
Total liabilities		129,178	118,691	114,758
Net assets		186,862	179,811	171,640
Granite’s share of net assets		$ 75,625	$ 75,287	$ 74,511

[1] The balance primarily related to local bank debt for equipment purchases and working capital in our foreign affiliates and debt associated with our real estate investments.