Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Currency Swaps Outstanding (Details) £ in Millions	Sep. 30, 2025 GBP (£)
250 million Sterling currency swap
Derivative
Effective Date of Currency Swap Contract	2001
Associated TVA bond issues currency exposure	£ 250
Expiration Date of Swap	2032
Overall effective cost to TVA	6.587%
150 million Sterling currency swap
Derivative
Effective Date of Currency Swap Contract	2003
Associated TVA bond issues currency exposure	£ 150
Expiration Date of Swap	2043
Overall effective cost to TVA	4.962%