Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Allowance for uncollectible accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 29	$ 20	$ 20
Charged to Expense	22	33	29
Charged to Other Accounts	0	0	0
Deductions	31	24	29
Balance at End of Period	20	29	20
Allowance for uncollectible accounts | Consumers Energy Company
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	29	20	20
Charged to Expense	22	33	29
Charged to Other Accounts	0	0	0
Deductions	31	24	29
Balance at End of Period	20	29	20
Deferred tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	1	2	8
Charged to Expense	1	0	0
Charged to Other Accounts	0	0	0
Deductions	0	1	6
Balance at End of Period	$ 2	$ 1	$ 2