Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Accounts receivable and accrued revenue, ALLOWANCE	$ 24	$ 29
Common stock authorized (in shares)	350,000,000.0	350,000,000.0
Common stock outstanding (in shares)	289,700,000	288,900,000
Preferred stock authorized (in shares)	9,200,000
Preferred stock outstanding (in shares)	9,200,000
Consumers Energy Company
Accounts receivable and accrued revenue, ALLOWANCE	$ 24	$ 29
Common stock authorized (in shares)	125,000,000.0	125,000,000.0
Common stock outstanding (in shares)	84,100,000	84,100,000
Preferred stock authorized (in shares)	7,500,000	7,500,000
Preferred stock outstanding (in shares)	400,000	400,000