Contingencies And Commitments (Contingencies And Commitments) (Details) violation in Thousands	1 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) violation site	Jan. 31, 2019 USD ($)	Jun. 30, 2019 USD ($) site lawsuit	Dec. 31, 2018 USD ($)
Loss Contingencies [Line Items]
Regulatory assets	$ 2,344,000,000		$ 2,344,000,000	$ 1,743,000,000
Consumers Energy Company
Loss Contingencies [Line Items]
Regulatory assets	2,344,000,000		2,344,000,000	$ 1,743,000,000
Bay Harbor
Loss Contingencies [Line Items]
Accrual for obligations for environmental remediation	$ 45,000,000		$ 45,000,000
Discounted projected costs rate	4.34%		4.34%
Remaining undiscounted obligation amount	$ 56,000,000		$ 56,000,000
Accrual for environmental loss contingencies, inflation rate	1.00%		1.00%
Electric Utility | NREPA | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for obligations for environmental remediation	$ 3,000,000		$ 3,000,000
Electric Utility | NREPA | Minimum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs	3,000,000		3,000,000
Electric Utility | NREPA | Maximum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs	4,000,000		4,000,000
Electric Utility | CERCLA Liability | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for obligations for environmental remediation	3,000,000		3,000,000
Electric Utility | CERCLA Liability | Minimum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs	3,000,000		3,000,000
Electric Utility | CERCLA Liability | Maximum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs	8,000,000		8,000,000
Gas Utility | NREPA | Maximum | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for obligations for environmental remediation	1,000,000		1,000,000
Remediation and other response activity costs	3,000,000		3,000,000
Gas Utility | Manufactured Gas Plant | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for obligations for environmental remediation	$ 68,000,000		$ 68,000,000
Discounted projected costs rate	2.57%		2.57%
Remaining undiscounted obligation amount	$ 74,000,000		$ 74,000,000
Number of former MGPs | site	23		23
Accrual for environmental loss contingencies, inflation rate	2.50%		2.50%
Authorized recovery, collection period			10 years
Regulatory assets	$ 129,000,000		$ 129,000,000
Equatorial Guinea Tax Claim
Loss Contingencies [Line Items]
Foreign government tax claim on sale			$ 152,000,000
Class Action Lawsuits
Loss Contingencies [Line Items]
Number of lawsuits | lawsuit			4
Individual Lawsuits
Loss Contingencies [Line Items]
Number of lawsuits | lawsuit			1
MCV PPA | Consumers Energy Company
Loss Contingencies [Line Items]
Foreign government tax claim on sale		$ 270,000,000
Underwater cables Straits of Mackinac | Maximum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs	$ 10,000,000		$ 10,000,000
MPSC Gas Staking MISS DIG Act [Member] | Consumers Energy Company
Loss Contingencies [Line Items]
Number of alleged violations | violation	20
Maximum possible loss per violation	$ 5,000