Note 12 - Investments in Affiliates - Equity Method Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Total investments in affiliates	$ 73,249	$ 84,176	$ 81,034
Foreign Affiliates [Member]
Total investments in affiliates	45,598	55,335	56,082
Real Estate Entities [Member]
Total investments in affiliates	16,651	17,229	16,433
Asphalt Terminal Entity [Member]
Total investments in affiliates	$ 11,000	$ 11,612	$ 8,519