XML 181 R91.htm IDEA: XBRL DOCUMENT v3.23.3
Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Counterparty Credit Risk (Details)
$ in Millions
12 Months Ended
Sep. 30, 2023
USD ($)
Customers
Sep. 30, 2022
USD ($)
Derivative    
Receivables from power sales | $ $ 1,627 $ 1,899
Credit of Customers    
Derivative    
Number of customers that represent the percent of sales | Customers 2