Note 3 - Business Combinations - Intangible Assets Acquired (Details) - Geneva Pipe Company, Inc. [Member] $ in Thousands	Jan. 31, 2020 USD ($)
Intangible Asset Acquired, Useful Life (Year)	9 years 10 months 24 days
Intangible Asset Acquired, Fair Value	$ 11,165
Customer Relationships [Member]
Intangible Asset Acquired, Useful Life (Year)	11 years
Intangible Asset Acquired, Fair Value	$ 8,031
Trade Names [Member]
Intangible Asset Acquired, Useful Life (Year)	10 years
Intangible Asset Acquired, Fair Value	$ 2,093
Backlog [Member]
Intangible Asset Acquired, Useful Life (Year)	10 months 24 days
Intangible Asset Acquired, Fair Value	$ 1,041