Contingencies and Commitments (Narrative) (Details) $ in Millions	1 Months Ended			12 Months Ended					24 Months Ended
	Jul. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2022 USD ($) $ / MWh $ / MW site MW	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2021 USD ($)
Loss Contingencies [Line Items]
Regulatory assets				$ 3,595		$ 2,259			$ 2,259
Environmental Loss Contingency, Statement Of Financial Position, Extensible Enumeration, Not Disclosed Flag				recorded liability
Consumers Energy Company
Loss Contingencies [Line Items]
Regulatory assets				$ 3,595		2,259			2,259
Cost of gas sold				1,243		726		$ 568
Plant additions				$ 2,300		2,400
Consumers Energy Company | MCV PPA
Loss Contingencies [Line Items]
PPA minimum quantity required | MW				1,240
PPA fixed energy charge per MWh, on-peak (in dollars per MWh) | $ / MWh				6.30
PPA fixed energy charge per MWh, off-peak (in dollars per MWh) | $ / MWh				6.00
Annual contribution to renewable resources program by counterparty				$ 5
Purchases				$ 519		348		298
Consumers Energy Company | MCV PPA | Year End Through March 2025
Loss Contingencies [Line Items]
PPA capacity charge per MWh (in dollars per MWh) | $ / MW				10.14
Consumers Energy Company | MCV PPA | March 2025 Through Termination
Loss Contingencies [Line Items]
PPA capacity charge per MWh (in dollars per MWh) | $ / MW				5.00
Consumers Energy Company | Other PPAs
Loss Contingencies [Line Items]
Purchases				$ 510		338		$ 327
Consumers Energy Company | GCR underrecoveries
Loss Contingencies [Line Items]
Cost of gas sold					$ 700		$ 400
Consumers Energy Company | Ray Compressor Station
Loss Contingencies [Line Items]
Plant additions									17
Insurance recoveries received				13
Impairment charge				10
Consumers Energy Company | Ray Compressor Station | GCR underrecoveries
Loss Contingencies [Line Items]
Cost of gas sold			$ 7
Consumers Energy Company | MGP Sites
Loss Contingencies [Line Items]
Regulatory assets				$ 108		$ 112			$ 112
Consumers Energy Company | Ludington
Loss Contingencies [Line Items]
Ownership share				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
Bay Harbor
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies				$ 45
Discount rate				4.34%
Accrual for environmental loss contingencies, inflation rate				1.00%
Accrual for environmental loss contingencies, gross				$ 57
NREPA | Electric Utility | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies				2
NREPA | Gas Utility | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies				1
NREPA | Minimum | Electric Utility | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs				2
NREPA | Maximum | Electric Utility | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs				4
NREPA | Maximum | Gas Utility | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs				3
CERCLA Liability | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies				3
CERCLA Liability | Minimum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs				3
CERCLA Liability | Maximum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs				8
MGP Sites | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies				$ 62
Discount rate				2.57%
Accrual for environmental loss contingencies, inflation rate				2.50%
Accrual for environmental loss contingencies, gross				$ 67
Number of former MGPs | site				23
Regulatory asset collection period				10 years