Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Assets
Restricted cash equivalents	$ 19	$ 24
Derivative instruments	4	2
Liabilities
Derivative instruments	4	7
Consumers Energy Company
Assets
Restricted cash equivalents	18	22
Derivative instruments	3	2
Liabilities
Derivative instruments	0	0
Fair Value, Inputs, Level 1
Assets
Restricted cash equivalents	19	24
Nonqualified deferred compensation plan assets	23	27
Liabilities
Nonqualified deferred compensation plan liabilities	23	27
Fair Value, Inputs, Level 1 | Consumers Energy Company
Assets
Restricted cash equivalents	18	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	46	53
Liabilities
Total liabilities	27	34
Fair Value, Inputs, Level 1, 2 and 3 | Consumers Energy Company
Assets
Total assets	38	45
Liabilities
Total liabilities	$ 17	$ 21