Commitments and Contingencies - Leases (Details) - USD ($)
$ in Millions

Sep. 30, 2021

Sep. 30, 2020

Sep. 30, 2019

Leases

CT and QTE outstanding leaseback obligation

$ 25

$ 223

Estimated future decommissioning cost

^[1]

$ 7,002

$ 6,785

$ 5,616

[1]

(1) Includes $266 million and $345 million at September 30, 2021 and 2020, respectively, in Current liabilities.

TVA implemented revised depreciation rates during the first quarter of 2022 applicable to its completed plant as a result of the completion of a new depreciation study. The study includes a decline in the service life estimates of TVA’s coal-fired plants based on current planning assumptions to potentially retire the remainder of the coal-fired fleet by 2035. As a result of the accelerated retirements reflected in the depreciation study, TVA performed an assessment of the assumptions used in the timing of cash flows related to its non-nuclear AROs. Based on the assessment, TVA identified changes to its projections of timing of certain asset retirement processes, that will be recorded in 2022.