Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Assets
Restricted cash equivalents	$ 27	$ 24
Derivative instruments	3	2
Liabilities
Derivative instruments	0	7
Consumers Energy Company
Assets
Restricted cash equivalents	27	22
Derivative instruments	3	2
Liabilities
Derivative instruments	0	0
Fair Value, Inputs, Level 1
Assets
Restricted cash equivalents	27	24
Nonqualified deferred compensation plan assets	22	27
Liabilities
Nonqualified deferred compensation plan liabilities	22	27
Fair Value, Inputs, Level 1 | Consumers Energy Company
Assets
Restricted cash equivalents	27	22
Nonqualified deferred compensation plan assets	17	21
Liabilities
Nonqualified deferred compensation plan liabilities	17	21
Fair Value, Inputs, Level 1, 2 and 3
Assets
Total assets	52	53
Liabilities
Total liabilities	22	34
Fair Value, Inputs, Level 1, 2 and 3 | Consumers Energy Company
Assets
Total assets	47	45
Liabilities
Total liabilities	$ 17	$ 21