v3.26.1
Fair Value Measurements - Assets Measured at Fair Value on Non-Recurring Basis (Detail) - USD ($)
$ in Millions
May 31, 2026
May 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure $ 76.8  
Fair Value, Nonrecurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure 77.3 $ 10.4
Fair Value, Nonrecurring | Long-Lived Assets, Intangible Assets, and Other Assets - Electrical Steel    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure [1] 76.8  
Fair Value, Nonrecurring | Long-Lived Assets Held and Used - Taylor    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure [2] 0.5  
Fair Value, Nonrecurring | Long Lived Assets Held For Sale    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure [3]   10.4
Fair Value, Nonrecurring | Fair Value, Inputs, Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure 0.0 0.0
Fair Value, Nonrecurring | Fair Value, Inputs, Level 1 | Long-Lived Assets, Intangible Assets, and Other Assets - Electrical Steel    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure [1] 0.0  
Fair Value, Nonrecurring | Fair Value, Inputs, Level 1 | Long-Lived Assets Held and Used - Taylor    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure [2] 0.0  
Fair Value, Nonrecurring | Fair Value, Inputs, Level 1 | Long Lived Assets Held For Sale    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure [3]   0.0
Fair Value, Nonrecurring | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure 0.0 0.0
Fair Value, Nonrecurring | Fair Value, Inputs, Level 2 | Long-Lived Assets, Intangible Assets, and Other Assets - Electrical Steel    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure [1] 0.0  
Fair Value, Nonrecurring | Fair Value, Inputs, Level 2 | Long-Lived Assets Held and Used - Taylor    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure [2] 0.0  
Fair Value, Nonrecurring | Fair Value, Inputs, Level 2 | Long Lived Assets Held For Sale    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure [3]   0.0
Fair Value, Nonrecurring | Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure 77.3 10.4
Fair Value, Nonrecurring | Fair Value, Inputs, Level 3 | Long-Lived Assets, Intangible Assets, and Other Assets - Electrical Steel    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure [1] 76.8  
Fair Value, Nonrecurring | Fair Value, Inputs, Level 3 | Long-Lived Assets Held and Used - Taylor    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure [2] $ 0.5  
Fair Value, Nonrecurring | Fair Value, Inputs, Level 3 | Long Lived Assets Held For Sale    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets, Fair Value Disclosure [3]   $ 10.4
[1] During fiscal 2026, the Company measured the fair values of certain long-lived asset groups and the Electrical Steel reporting unit in connection with the impairment analyses performed. These fair value measurements were classified within Level 3 of the fair value hierarchy because they included significant unobservable inputs. The fair values of the affected long-lived asset groups were determined using a discounted cash flow method, market approach, cost approach, or combination thereof, which included significant unobservable inputs. The affected long-lived asset groups were written down to the estimated fair value of $76.8 million. The fair value of the Electrical Steel reporting unit was estimated using an income approach based on discounted projected cash flows. Based on the results of the quantitative impairment test, the carrying amount of the Electrical Steel reporting unit exceeded its estimated fair value. The impairment was measured as the excess of the reporting unit’s carrying amount over its estimated fair value, limited to the carrying amount of goodwill assigned to the Electrical Steel reporting unit. The carrying amount of the goodwill of the Electrical Steel reporting unit was fully impaired. Refer to “Note 5 – Goodwill, Long-Lived Assets, and Other Assets” for additional information regarding the valuation methodology, significant unobservable inputs and impairment charges recognized.
[2] During fiscal 2026, the net asset value of certain machinery at the manufacturing facility in Taylor, Michigan was lowered to $0.5 million based on prices for similar assets. Refer to “Note 5 – Goodwill, Long-Lived Assets, and Other Assets” for additional information.
[3] During the third quarter of fiscal 2025, the Company announced plans to combine WSCP’s Cleveland, Ohio toll processing manufacturing facility into its existing manufacturing facility in Twinsburg, Ohio. At that time, the Company determined there was no impairment related to finance lease assets along with certain other fixed assets encumbered to the land and building of the finance lease assets. Certain machinery and equipment fixed assets and other long-lived assets were written down to their estimated fair value of $1.3 million based on estimated replacement costs and/or prices for similar assets. During the fourth quarter of fiscal 2025, the Company transferred the remaining $10.4 million to assets held for sale, which represented the remaining net assets prior to the held for sale criteria being met. The assets held for sale are expected to be disposed of primarily by sales within the next twelve months.