Note 19 - Segment Information - Information Related to the Operations of the Company's Operating Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net sales	$ 457,665	$ 333,313	$ 285,907
Gross profit	85,855	44,254	50,519
Depreciation and amortization	17,103	13,624	14,551
Capital expenditures	22,829	13,262	14,013
Total assets	601,340	547,679
Operating Segments [Member]
Depreciation and amortization	16,596	13,262	14,153
Capital expenditures	22,136	12,793	13,428
Total assets	564,444	537,446
Operating Segments [Member] | Engineered Steel Pressure Pipe [Member]
Net sales	307,572	259,823	241,690
Gross profit	44,473	31,281	44,293
Depreciation and amortization	9,789	9,524	10,746
Capital expenditures	8,211	7,538	12,031
Total assets	307,924	308,819
Operating Segments [Member] | Precast Infrastructure and Engineered Systems [Member]
Net sales	150,093	73,490	44,217
Gross profit	41,382	12,973	6,226
Depreciation and amortization	6,807	3,738	3,407
Capital expenditures	13,925	5,255	1,397
Total assets	256,520	228,627
Corporate, Non-Segment [Member]
Depreciation and amortization	507	362	398
Capital expenditures	693	469	$ 585
Total assets	$ 36,896	$ 10,233