Revenue Recognition - Revenue by Product Class and Timing (Detail) - USD ($) $ in Thousands	3 Months Ended
	Aug. 31, 2023	Aug. 31, 2022
Disaggregation Of Revenue [Line Items]
Net sales	$ 1,193,256	$ 1,408,665
Steel Processing
Disaggregation Of Revenue [Line Items]
Net sales	881,339	1,038,880
Direct | Steel Processing
Disaggregation Of Revenue [Line Items]
Net sales	845,363	1,002,135
Toll | Steel Processing
Disaggregation Of Revenue [Line Items]
Net sales	35,976	36,745
Toll | Steel Processing | Over time revenue
Disaggregation Of Revenue [Line Items]
Net sales	35,976	36,745
Building Products
Disaggregation Of Revenue [Line Items]
Net sales	133,868	150,323
Consumer products
Disaggregation Of Revenue [Line Items]
Net sales	149,412	188,703
Sustainable Energy Solutions
Disaggregation Of Revenue [Line Items]
Net sales	$ 28,637	$ 30,759