Financings And Capitalization (Narrative) (Details)	6 Months Ended
	Jun. 30, 2017 USD ($)
Financing And Capitalization [Line Items]
Unrestricted retained earnings	$ 4,400,000,000
Common stock dividends from Consumers	236,000,000
Term Loan [Member]
Financing And Capitalization [Line Items]
Debt issuance	$ 180,000,000
Debt instrument, extension term	1 year
Consumers Energy Company [Member]
Financing And Capitalization [Line Items]
Unrestricted retained earnings	$ 1,100,000,000
Consumers Energy Company [Member] | Commercial Paper [Member]
Financing And Capitalization [Line Items]
Short-term debt, authorized borrowings	500,000,000
Short-term borrowings outstanding	$ 0