Notes Receivable (Schedule Of Allowance For Loan Losses) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Notes, Loans, And Financing Receivable, Net Rollforward [Roll Forward]
Allowance for loan losses, at beginning of period	$ 123	$ 33
Provision for loan losses	5	13
Charge-offs	(12)	(11)
Recoveries	2	2
Allowance for loan losses, at end of period	118	99
Cumulative Effect, Period of Adoption, Adjustment | EnerBank
Notes, Loans, And Financing Receivable, Net Rollforward [Roll Forward]
Allowance for loan losses, at beginning of period	$ 0	$ 62