Financings And Capitalization (Narrative) (Details)		1 Months Ended	6 Months Ended
	Jul. 01, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($)	Jun. 30, 2021 USD ($)
Financing And Capitalization [Line Items]
Limitation on payment of stock dividends			$ 5,800,000,000
Dividends paid			380,000,000
Stock offering program maximum value			500,000,000
Series C Preferred Stock Depositary Shares | Subsequent Event
Financing And Capitalization [Line Items]
Depositary share conversion ratio	0.001
Number of shares issued (in shares) | shares	9,200,000
Issue price (in dollars per share) | $ / shares	$ 25.00
Proceeds from issuance of preferred stock	$ 224,000,000
Dividend rate	4.20%
Optional redemption price (in dollars per share) | $ / shares	$ 25.00
Series C Preferred Stock | Subsequent Event
Financing And Capitalization [Line Items]
Optional redemption price (in dollars per share) | $ / shares	$ 25,000
Consumers Energy Company
Financing And Capitalization [Line Items]
Notes payable – related parties		$ 307,000,000	0
Unrestricted retained earnings			1,800,000,000
Consumers Energy Company | Credit Agreement
Financing And Capitalization [Line Items]
Maximum borrowing capacity		$ 350,000,000
Notes payable – related parties			0
Consumers Energy Company | Credit Agreement | London Interbank Offered Rate (LIBOR)
Financing And Capitalization [Line Items]
Basis spread on variable rate		0.10%
Consumers Energy Company | Commercial Paper
Financing And Capitalization [Line Items]
Short-term debt authorized borrowings			500,000,000
Short-term borrowings outstanding			$ 0