Notes Receivable (Schedule Of Current And Non-Current Notes Receivable) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
EnerBank notes receivable, net of allowance for loan losses	$ 284	$ 275
Total notes receivable	2,710	2,887
Consumers Energy Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
DB SERP note receivable – related party	7	7
DB SERP note receivable – related party	99	100
Total notes receivable	106	107
EnerBank
Accounts, Notes, Loans and Financing Receivable [Line Items]
EnerBank notes receivable, net of allowance for loan losses	284	275
EnerBank notes receivable, net of allowance for loan losses	$ 2,426	$ 2,612