Notes Receivable (Schedule Of Current And Non-Current Notes Receivable) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	$ 146	$ 128
EnerBank notes receivable held for sale	41	16
Total notes receivable	1,286	1,161
Consumers Energy Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	45
EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Noncurrent notes receivable	1,051	1,017
Receivables, Net Of Allowance For Loan Losses [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	146	128
Receivables Held For Sale [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
EnerBank notes receivable held for sale	41	$ 16
State Of Michigan Tax Settlement [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Noncurrent notes receivable	48
State Of Michigan Tax Settlement [Member] | Consumers Energy Company [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Noncurrent notes receivable	$ 45