Accounts Receivable, Net Accounts Receivable, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Power receivables	$ 1,908	$ 1,683
Other receivables	225	118
Accounts receivable, net	2,119	1,801
Allowance for uncollectible accounts - receivables	14	1	[1]
Accounts Receivable, Allowance for Credit Loss	(14)	$ 0
Tax Credits Reduce Net Completed Plant	51
Tax Credits Reduce Operating & Maintenance Expense	19
Tax Credits Interest Income Recorded	2
Other Receivables, Net, Current	72
Investment Tax Credit	26
Holly Springs
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for uncollectible accounts - receivables	$ 14

[1] determine the allowance for trade receivables, TVA considers historical experience and other currently available information, including events such as customer bankruptcy and/or a customer failing to fulfill payment arrangements by the due date, among other considerations. See Note 1 — Summary of Significant Accounting Policies — Allowance for Uncollectible Accounts. At September 30, 2025, the allowance for uncollectible accounts included $14 million related to one LPC customer. (2) The allowance for uncollectible accounts was less than $1 million at September 30, 2024. In addition, the Inflation Reduction Act of 2022 ("IRA") makes credits available to certain tax-exempt entities, including TVA. Obtaining this funding requires TVA to meet certain requirements, to submit informational returns to the Internal Revenue Service ("IRS"), and to retain adequate books and records to support its filings. TVA records the credit when there is reasonable assurance that the credit will be received, and TVA complies with all conditions attached to the eligibility of the credit. The credit is recognized as a reduction of the asset and/or expense based on what the credits are intended to reimburse. At September 30, 2025, TVA recorded $72 million in Accounts receivable, net, which is classified as Other receivables above, related to these tax credits; $51 million was recorded as a reduction of Net completed plant; $19 million was recorded to reduce Operating and maintenance expense; and $2 million related to interest was recorded to Other income, net. There were no tax credits recorded in 2024. TVA received $26 million in October 2025 related to these credits.