Contingencies And Commitments (Contingencies And Commitments) (Details)
$ in Millions |
9 Months Ended |
|
|
Sep. 30, 2016
USD ($)
item
lawsuit
|
Dec. 31, 2015
USD ($)
|
| Loss Contingencies [Line Items] |
|
|
| Regulatory assets |
$ 1,765
|
$ 1,840
|
| Consumers Energy Company [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Regulatory assets |
1,765
|
$ 1,840
|
| Bay Harbor [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Demand for payment by USEPA |
8
|
|
| Accrual for environmental loss contingencies |
$ 52
|
|
| Discounted projected costs rate |
4.34%
|
|
| Remaining undiscounted obligation amount |
$ 67
|
|
| Accrual for environmental loss contingencies, inflation rate |
1.00%
|
|
| Electric Utility [Member] | NREPA [Member] | Consumers Energy Company [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Accrual for environmental loss contingencies |
$ 3
|
|
| Electric Utility [Member] | NREPA [Member] | Minimum [Member] | Consumers Energy Company [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Remediation and other response activity costs |
3
|
|
| Electric Utility [Member] | NREPA [Member] | Maximum [Member] | Consumers Energy Company [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Remediation and other response activity costs |
4
|
|
| Electric Utility [Member] | CERCLA Liability [Member] | Consumers Energy Company [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Accrual for environmental loss contingencies |
3
|
|
| Electric Utility [Member] | CERCLA Liability [Member] | Minimum [Member] | Consumers Energy Company [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Remediation and other response activity costs |
3
|
|
| Electric Utility [Member] | CERCLA Liability [Member] | Maximum [Member] | Consumers Energy Company [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Remediation and other response activity costs |
8
|
|
| Gas Utility [Member] | NREPA [Member] | Maximum [Member] | Consumers Energy Company [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Accrual for environmental loss contingencies |
1
|
|
| Remediation and other response activity costs |
3
|
|
| Gas Utility [Member] | Manufactured Gas Plant [Member] | Consumers Energy Company [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Accrual for environmental loss contingencies |
$ 108
|
|
| Discounted projected costs rate |
2.57%
|
|
| Remaining undiscounted obligation amount |
$ 118
|
|
| Number of former MGPs | item |
23
|
|
| Regulatory assets |
$ 140
|
|
| Authorized recovery, collection period |
10 years
|
|
| Accrual for environmental loss contingencies, inflation rate |
2.50%
|
|
| Equatorial Guinea Tax Claim [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Foreign government tax claim on sale |
$ 152
|
|
| Class Action Lawsuits [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Number of lawsuits | lawsuit |
4
|
|
| Individual Lawsuits [Member] |
|
|
| Loss Contingencies [Line Items] |
|
|
| Number of lawsuits | lawsuit |
1
|
|