Note 12 - Investments in Affiliates - Summarized Balance Sheet Information for Equity Method Investments (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Current assets		$ 1,301,064	$ 1,376,941	$ 1,209,845
Total assets		2,384,375	2,502,088	2,358,603
Current liabilities		809,562	842,056	675,777
Granite’s share of net assets		73,249	84,176	81,034
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Current assets		112,426	122,348	137,041
Noncurrent assets		163,452	165,331	179,377
Total assets		275,878	287,679	316,418
Current liabilities		45,617	48,322	65,848
Long-term liabilities (1)	[1]	57,182	61,078	75,949
Total liabilities		102,799	109,400	141,797
Net assets		173,079	178,279	174,621
Granite’s share of net assets		$ 73,249	$ 84,176	$ 81,034

[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.