v3.26.1
Goodwill, Long-Lived Assets, and Other Assets - Additional Information (Detail)
 3 Months Ended 12 Months Ended
Feb. 28, 2025
USD ($)
May 31, 2026
USD ($)
UnrelatedAssets
May 31, 2025
USD ($)
May 31, 2024
USD ($)
Goodwill And Other Intangible Assets [Line Items]        
Goodwill   $ 44,500,000 $ 79,600,000 $ 79,600,000
Amortization expense   $ 8,200,000 6,000,000 6,300,000
Discounted market-participant rate   11.00%    
Pre-tax impairment charge   $ 114,300,000 7,400,000 1,400,000
Pre-tax impairment charge   $ 58,400,000    
Impairment, Long-Lived Asset, Held-for-Use, Statement of Income or Comprehensive Income [Extensible Enumeration]   Impairment of long lived assets and other assets    
Pre-tax goodwill impairment charge   $ 53,800,000 0 0
Assets held for sale   $ 9,100,000 11,500,000  
Number of unrelated asset | UnrelatedAssets   3    
Impairment charge of long-lived assets     0 1,400,000
Impairment of goodwill   $ 53,800,000 [1] 0 0
Operating lease assets   77,800,000 72,600,000  
Estimate of fair value less costs to sell       $ 200,000
Machinery and Equipment and Other Long-lived Assets        
Goodwill And Other Intangible Assets [Line Items]        
Pre-tax impairment charge   600,000    
Construction in Progress        
Goodwill And Other Intangible Assets [Line Items]        
Pre-tax impairment charge   1,500,000    
Tempel Canada        
Goodwill And Other Intangible Assets [Line Items]        
Impairment charge of long-lived assets   0    
Disposal Group Held for Use        
Goodwill And Other Intangible Assets [Line Items]        
Pre-tax impairment charge     6,100,000  
Impairment charge of long-lived assets     5,600,000  
Carrying value long-lived assets     17,000,000  
Disposal Group Held for Use | Machinery and Equipment and Other Long-lived Assets        
Goodwill And Other Intangible Assets [Line Items]        
Impairment charge of long-lived assets     3,800,000  
Disposal Group Held for Use | Finance Lease Assets and Buildings and Improvements, Net        
Goodwill And Other Intangible Assets [Line Items]        
Impairment charge of long-lived assets     0  
Disposal Group Assets Held For Sale        
Goodwill And Other Intangible Assets [Line Items]        
Assets held for sale     $ 10,400,000  
Disposal Group Assets Held For Sale | Tempel Canada        
Goodwill And Other Intangible Assets [Line Items]        
Assets held for sale   $ 8,600,000    
In Process Research and Development        
Goodwill And Other Intangible Assets [Line Items]        
Pre-tax impairment charge $ 1,300,000      
Intangible asset net book value prior to impairment $ 1,300,000      
Minimum        
Goodwill And Other Intangible Assets [Line Items]        
Definite-lived intangible assets, estimated useful lives   3 years    
Maximum        
Goodwill And Other Intangible Assets [Line Items]        
Definite-lived intangible assets, estimated useful lives   20 years    
[1] A pre-tax goodwill impairment charge of $53.8 million that fully impaired the goodwill assigned to the Electrical Steel reporting unit.