Notes Receivable (Schedule Of Allowance For Loan Losses) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2020
Notes, Loans, And Financing Receivable, Net Rollforward [Roll Forward]
Allowance for loan losses, at beginning of period	$ 33	$ 24
Provision for loan losses	60	38
Charge-offs	(39)	(35)
Recoveries	7	6
Allowance for loan losses, at end of period	123	33
Unfunded Loan Commitment \| EnerBank
Notes, Loans, And Financing Receivable, Net Rollforward [Roll Forward]
Allowance for expected credit loss on off balance sheet commitments	6
Cumulative Effect, Period of Adoption, Adjustment \| EnerBank
Notes, Loans, And Financing Receivable, Net Rollforward [Roll Forward]
Allowance for loan losses, at beginning of period	$ 62	0
Allowance for loan losses, at end of period		$ 62
Cumulative Effect, Period of Adoption, Adjustment \| Unfunded Loan Commitment \| EnerBank
Notes, Loans, And Financing Receivable, Net Rollforward [Roll Forward]
Allowance for expected credit loss on off balance sheet commitments			$ 3

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount of increase in allowance for credit loss on financing receivable from recovery.

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Amount of writeoff of financing receivable, charged against allowance for credit loss.

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Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

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Amount of credit loss expense (reversal of expense) for financing receivable.

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