v3.26.1
Fair Value Measurements - Summary of Fair Values of Outstanding Natural Gas Derivatives (Details) - Commodity Contract [Member] - USD ($)
$ in Millions
Jun. 30, 2026
Sep. 30, 2025
Accounts Receivable [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Commodity derivative assets [1] $ 0 $ 1
Notional contract values 2 6
Accrued Expenses and Other Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Commodity derivative liabilities 2 1
Notional contract values $ 16 $ 7
[1] Zero denotes less than $1 million of activity.