Operating segments (Details) - USD ($) $ in Thousands	3 Months Ended
	May 31, 2023	May 31, 2022	Feb. 28, 2023
Operations and assets by segment
Sales	$ 390,873	$ 207,134
Cost of sales	293,854	147,081
Gross margin	97,019	60,053
Selling, general and administrative	31,523	32,144
Operating income (loss)	65,496	27,909
Interest expense	28,706	7,472
Equity in (earnings) loss of unconsolidated subsidiaries	(1,420)	0
Other (income) expense	38	(27)
Income taxes	9,650	5,111
Net income from continuing operations	28,522	15,353
Income (loss) from continuing operations before income tax	38,172	20,464
Assets:	2,205,977		$ 2,221,479
Property, plant and equipment, net	504,032		498,503
United States
Operations and assets by segment
Sales	381,322	194,360
Property, plant and equipment, net	484,305		478,722
Canada
Operations and assets by segment
Sales	9,551	12,774
Property, plant and equipment, net	19,727		19,781
Corporate
Operations and assets by segment
Sales	0	0
Cost of sales	0	0
Gross margin	0	0
Selling, general and administrative	17,643	24,009
Operating income (loss)	(17,643)	(24,009)
Interest expense	28,706	7,472
Equity in (earnings) loss of unconsolidated subsidiaries	0
Other (income) expense	38	(27)
Income taxes	9,650	5,111
Net income from continuing operations	(56,037)	(36,565)
Income (loss) from continuing operations before income tax	(46,387)	(31,454)
Assets:	46,610		59,572
Metal Coatings | Operating Segments
Operations and assets by segment
Sales	168,794	163,443
Cost of sales	117,858	113,580
Gross margin	50,936	49,863
Selling, general and administrative	5,466	4,593
Operating income (loss)	45,470	45,270
Assets:	582,664		588,337
Precoat Metals | Operating Segments
Operations and assets by segment
Sales	222,079	43,691
Cost of sales	175,996	33,501
Gross margin	46,083	10,190
Selling, general and administrative	8,392	3,542
Operating income (loss)	37,691	6,648
Assets:	1,489,635		1,488,810
Infrastructure Solutions | Operating Segments
Operations and assets by segment
Sales	0	0
Cost of sales	0	0
Gross margin	0	0
Selling, general and administrative	22	0
Operating income (loss)	(22)	0
Interest expense	0	0
Equity in (earnings) loss of unconsolidated subsidiaries	(1,420)
Other (income) expense	0	0
Income (loss) from continuing operations before income tax	1,398	$ 0
Assets:	$ 87,068		$ 84,760