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Summary of Significant Accounting Policies [Table Text Block]

12 Months Ended

Sep. 30, 2021

Accounting Policies [Abstract]

Property, Plant, and Equipment Depreciation Rates

Average depreciation rates by asset class are as follows:

Property, Plant, and Equipment Depreciation Rates At September 30 (percent)
			2021						2020						2019
Asset Class
Nuclear			2.38						2.38						2.38
Coal-fired(1)			1.95						3.62						4.96
Hydroelectric			1.60						1.60						1.61
Gas and oil-fired			2.98						3.04						3.00
Transmission			1.34						1.34						1.34
Other			7.12						7.26						7.16

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Tabular disclosure of average depreciation rates by asset class.

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