Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Assets
Restricted cash equivalents	$ 18	$ 24
Derivative instruments	2	2
Liabilities
Derivative instruments	0	7
Consumers Energy Company
Assets
Restricted cash equivalents	17	22
Derivative instruments	2	2
Liabilities
Derivative instruments	0	0
Level 1
Assets
Restricted cash equivalents	18	24
Nonqualified deferred compensation plan assets	24	27
Liabilities
Nonqualified deferred compensation plan liabilities	24	27
Level 1 | Consumers Energy Company
Assets
Restricted cash equivalents	17	22
Nonqualified deferred compensation plan assets	18	21
Liabilities
Nonqualified deferred compensation plan liabilities	18	21
Fair Value, Inputs, Level 1, 2 and 3
Assets
Total assets	44	53
Liabilities
Total liabilities	24	34
Fair Value, Inputs, Level 1, 2 and 3 | Consumers Energy Company
Assets
Total assets	37	45
Liabilities
Total liabilities	$ 18	$ 21