Contingencies and Commitments (Contingencies And Commitments) (Details) $ in Millions	1 Months Ended			3 Months Ended		9 Months Ended		24 Months Ended
	Jul. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2022 USD ($) site	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) site	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Loss Contingencies [Line Items]
Regulatory assets				$ 3,427		$ 3,427		$ 2,259
Consumers Energy Company
Loss Contingencies [Line Items]
Regulatory assets				3,427		3,427		2,259
Cost of gas sold				$ 114	$ 53	$ 792	$ 425
Consumers Energy Company | Ludington
Loss Contingencies [Line Items]
Ownership share				51.00%		51.00%
Consumers Energy Company | Ludington Plant Overhaul Contract Dispute
Loss Contingencies [Line Items]
Damages sought		$ 15
Consumers Energy Company | J.H. Campbell 3 Plant Retirement Contract Dispute
Loss Contingencies [Line Items]
Damages sought	$ 37
Consumers Energy Company | Manufactured Gas Plant
Loss Contingencies [Line Items]
Regulatory assets				$ 111		$ 111
Bay Harbor
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies				$ 44		$ 44
Discounted projected costs rate				4.34%		4.34%
Accrual for environmental loss contingencies, inflation rate				1.00%		1.00%
Remaining undiscounted obligation amount				$ 54		$ 54
CERCLA Liability | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies				3		3
CERCLA Liability | Minimum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs				3		3
CERCLA Liability | Maximum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs				8		8
Manufactured Gas Plant | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies				$ 63		$ 63
Discounted projected costs rate				2.57%		2.57%
Accrual for environmental loss contingencies, inflation rate				2.50%		2.50%
Remaining undiscounted obligation amount				$ 67		$ 67
Number of former MGPs | site				23		23
Regulatory asset collection period						10 years
Electric Utility | NREPA | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies				$ 2		$ 2
Electric Utility | NREPA | Minimum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs				2		2
Electric Utility | NREPA | Maximum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs				4		4
Gas Utility | NREPA | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies				1		1
Gas Utility | NREPA | Maximum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs				$ 3		3
Ray Compressor Station | Consumers Energy Company
Loss Contingencies [Line Items]
Plant additions								$ 17
Insurance recoveries received						13
Impairment charge						$ 10
Ray Compressor Station | Consumers Energy Company | GCR underrecoveries
Loss Contingencies [Line Items]
Cost of gas sold			$ 7