Financings and Capitalization (Narrative) (Details)	1 Months Ended		12 Months Ended
	Jan. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)
Financing And Capitalization [Line Items]
Limitation on payment of stock dividends		$ 6,400,000,000	$ 6,400,000,000
Dividends paid			$ 722,000,000
Common stock authorized (in shares) | shares		350,000,000	350,000,000	350,000,000.0
Common stock, par value (in dollars per share) | $ / shares		$ 0.01	$ 0.01
Preferred stock authorized (in shares) | shares		10,000,000	10,000,000
Par value of preferred stock (in dollars per share) | $ / shares		$ 0.01	$ 0.01
Stock offering program maximum value			$ 500,000,000
Number of shares required to settle forward contracts (in shares) | shares		94,588	94,588
Issuance of preferred stock, net of issuance costs			$ 224,000,000	$ 0	$ 0
Series C Preferred Stock Depositary Shares
Financing And Capitalization [Line Items]
Preferred stock authorized (in shares) | shares		9,200,000	9,200,000
Number of shares issued (in shares) | shares		9,200,000	9,200,000
Depositary share conversion ratio		0.001	0.001
Issue price (in dollars per share) | $ / shares		$ 25.00	$ 25.00
Issuance of preferred stock, net of issuance costs			$ 224,000,000
Dividend rate			4.20%
Optional redemption price (in dollars per share) | $ / shares		25.00	$ 25.00
Trading Symbol			CMS PRC
Series C Preferred Stock
Financing And Capitalization [Line Items]
Optional redemption price (in dollars per share) | $ / shares		$ 25,000	$ 25,000
Consumers Energy Company Cumulative Preferred Stock, $100 par value: $4.50 Series
Financing And Capitalization [Line Items]
Trading Symbol			CMS-PB
Consumers Energy Company
Financing And Capitalization [Line Items]
Notes payable – related parties		$ 392,000,000	$ 392,000,000	$ 307,000,000
Unrestricted retained earnings		$ 1,800,000,000	$ 1,800,000,000
Common stock authorized (in shares) | shares		125,000,000.0	125,000,000.0	125,000,000.0
Preferred stock authorized (in shares) | shares		7,500,000	7,500,000	7,500,000
Consumers Energy Company | Credit Agreement
Financing And Capitalization [Line Items]
Maximum borrowing capacity		$ 500,000,000	$ 500,000,000
Notes payable – related parties		$ 392,000,000	$ 392,000,000
Interest rate		0.00%	0.00%
Consumers Energy Company | Credit Agreement | Subsequent Event
Financing And Capitalization [Line Items]
Repayment of note payable - related party	$ 392,000,000
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	$ 0