Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts receivable and accrued revenue, ALLOWANCE	$ 27	$ 29
Notes receivable, ALLOWANCE	29	32
Accounts and notes receivable, ALLOWANCE	$ 89	$ 91
Common stock authorized (in shares)	350,000,000.0	350,000,000.0
Common stock outstanding (in shares)	289,500,000	288,900,000
Consumers Energy Company
Accounts receivable and accrued revenue, ALLOWANCE	$ 27	$ 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