Revenue Recognition - Revenue by Product Class and Timing (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Nov. 30, 2022		Nov. 30, 2021		Nov. 30, 2022	Nov. 30, 2021
Disaggregation Of Revenue [Line Items]
Net sales	$ 1,175,541		$ 1,232,861		$ 2,584,206	$ 2,343,679
Steel Processing
Disaggregation Of Revenue [Line Items]
Net sales	841,947		937,842		1,880,827	1,760,652
Direct | Steel Processing
Disaggregation Of Revenue [Line Items]
Net sales	807,259		900,666		1,809,394	1,688,694
Toll | Steel Processing
Disaggregation Of Revenue [Line Items]
Net sales	34,688		37,176		71,433	71,958
Toll | Steel Processing | Over time revenue
Disaggregation Of Revenue [Line Items]
Net sales	34,688		37,176		71,433	71,958
Building Products
Disaggregation Of Revenue [Line Items]
Net sales	141,671	[1]	121,125	[1]	291,994	235,868
Consumer products
Disaggregation Of Revenue [Line Items]
Net sales	153,795	[1]	140,793	[1]	342,497	288,576
Sustainable Energy Solutions
Disaggregation Of Revenue [Line Items]
Net sales	$ 38,128	[1]	$ 33,101	[1]	$ 68,888	$ 58,583

[1] The products contained within each of these operating segments have similar production processes, require substantially the same raw materials, use similar equipment, and serve similar purposes. Therefore, we believe the products within each of these segments are appropriately combined for purposes of the disclosure requirements prescribed by Accounting Standards Codification (“ASC”) Topic 280 and Topic 606.