Note 11 - Investments in Affiliates - Summarized Balance Sheet Information for Equity Method Investments (Details) - USD ($) $ in Thousands		Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Current assets		$ 1,665,432	$ 1,455,246	$ 1,545,302
Total assets		2,561,756	2,379,996	2,488,273
Current liabilities		1,100,351	943,256	974,593
Granite’s share of net assets		72,415	75,287	76,464
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Current assets		162,503	133,882	116,712
Noncurrent assets		161,700	164,620	165,292
Total assets		324,203	298,502	282,004
Current liabilities		80,145	52,583	48,478
Long-term liabilities	[1]	59,501	66,108	55,206
Total liabilities		139,646	118,691	103,684
Net assets		184,557	179,811	178,320
Granite’s share of net assets		$ 72,415	$ 75,287	$ 76,464

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