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Retirement Benefits (Tables) | 9 Months Ended
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Sep. 30, 2011
Consumers Energy Company [Member] | Pension Plans, Defined Benefit [Member] |
Schedule of Net Benefit Costs |
In Millions
|  | Pension
|  | Three Months Ended |  |  | Nine Months Ended
September 30 |  | 2011 |  |  | 2010 |  |  | 2011 |  |  | 2010 |
CMS Energy, including Consumers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net periodic pension cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Service cost |  | $ | 12 |  |  | $ | 11 |  |  | $ | 36 |  |  | $ | 33 |
Interest expense |  |  | 25 |  |  |  | 25 |  |  |  | 75 |  |  |  | 74 |
Expected return on plan assets |  |  | (28 | ) |  |  | (24 | ) |  |  | (84 | ) |  |  | (70 | )
Amortization of: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net loss |  |  | 16 |  |  |  | 13 |  |  |  | 47 |  |  |  | 39 |
Prior service cost |  |  | 1 |  |  |  | 1 |  |  |  | 4 |  |  |  | 4 |
Net periodic pension cost |  | $ | 26 |  |  | $ | 26 |  |  | $ | 78 |  |  | $ | 80 |
Regulatory adjustment1 |  |  | — |  |  |  | 7 |  |  |  | — |  |  |  | 30 |
Net periodic pension cost after regulatory adjustment |  | $ | 26 |  |  | $ | 33 |  |  | $ | 78 |  |  | $ | 110 |
Consumers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net periodic pension cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Service cost |  | $ | 12 |  |  | $ | 11 |  |  | $ | 35 |  |  | $ | 32 |
Interest expense |  |  | 24 |  |  |  | 23 |  |  |  | 73 |  |  |  | 71 |
Expected return on plan assets |  |  | (27 | ) |  |  | (22 | ) |  |  | (82 | ) |  |  | (67 | )
Amortization of: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net loss |  |  | 15 |  |  |  | 13 |  |  |  | 46 |  |  |  | 38 |
Prior service cost |  |  | 1 |  |  |  | 1 |  |  |  | 4 |  |  |  | 4 |
Net periodic pension cost |  | $ | 25 |  |  | $ | 26 |  |  | $ | 76 |  |  | $ | 78 |
Regulatory adjustment1 |  |  | — |  |  |  | 7 |  |  |  | — |  |  |  | 30 |
Net periodic pension cost after regulatory adjustment |  | $ | 25 |  |  | $ | 33 |  |  | $ | 76 |  |  | $ | 108 |
1 Regulatory adjustments are the differences between amounts included in rates and the periodic benefit cost calculated. These regulatory adjustments were offset by surcharge revenues, resulting in no impact to net income for the periods presented.
Pension Plans, Defined Benefit [Member] |
Schedule of Net Benefit Costs |
In Millions |
|  | Pension |
|  | Three Months Ended |  |  | Nine Months Ended |
September 30 |  | 2011 |  |  | 2010 |  |  | 2011 |  |  | 2010 |
CMS Energy, including Consumers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net periodic pension cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Service cost |  | $ | 12 |  |  | $ | 11 |  |  | $ | 36 |  |  | $ | 33 |
Interest expense |  |  | 25 |  |  |  | 25 |  |  |  | 75 |  |  |  | 74 |
Expected return on plan assets |  |  | (28 | ) |  |  | (24 | ) |  |  | (84 | ) |  |  | (70 | )
Amortization of: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net loss |  |  | 16 |  |  |  | 13 |  |  |  | 47 |  |  |  | 39 |
Prior service cost |  |  | 1 |  |  |  | 1 |  |  |  | 4 |  |  |  | 4 |
Net periodic pension cost |  | $ | 26 |  |  | $ | 26 |  |  | $ | 78 |  |  | $ | 80 |
Regulatory adjustment1 |  |  | — |  |  |  | 7 |  |  |  | — |  |  |  | 30 |
Net periodic pension cost after regulatory adjustment |  | $ | 26 |  |  | $ | 33 |  |  | $ | 78 |  |  | $ | 110 |
Consumers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net periodic pension cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Service cost |  | $ | 12 |  |  | $ | 11 |  |  | $ | 35 |  |  | $ | 32 |
Interest expense |  |  | 24 |  |  |  | 23 |  |  |  | 73 |  |  |  | 71 |
Expected return on plan assets |  |  | (27 | ) |  |  | (22 | ) |  |  | (82 | ) |  |  | (67 | )
Amortization of: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net loss |  |  | 15 |  |  |  | 13 |  |  |  | 46 |  |  |  | 38 |
Prior service cost |  |  | 1 |  |  |  | 1 |  |  |  | 4 |  |  |  | 4 |
Net periodic pension cost |  | $ | 25 |  |  | $ | 26 |  |  | $ | 76 |  |  | $ | 78 |
Regulatory adjustment1 |  |  | — |  |  |  | 7 |  |  |  | — |  |  |  | 30 |
Net periodic pension cost after regulatory adjustment |  | $ | 25 |  |  | $ | 33 |  |  | $ | 76 |  |  | $ | 108 |
1 |  | Regulatory adjustments are the differences between amounts included in rates and the periodic benefit cost calculated. These regulatory adjustments were offset by surcharge revenues, resulting in no impact to net income for the periods presented.
Consumers Energy Company [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member] |
Schedule of Net Benefit Costs |
In Millions
|  | OPEB
|  | Three Months Ended |  |  | Nine Months Ended
September 30 |  | 2011 |  |  | 2010 |  |  | 2011 |  |  | 2010 |
CMS Energy, including Consumers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net periodic OPEB cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Service cost |  | $ | 7 |  |  | $ | 7 |  |  | $ | 20 |  |  | $ | 20 |
Interest expense |  |  | 20 |  |  |  | 20 |  |  |  | 58 |  |  |  | 61 |
Expected return on plan assets |  |  | (17 | ) |  |  | (16 | ) |  |  | (50 | ) |  |  | (45 | )
Amortization of: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net loss |  |  | 7 |  |  |  | 8 |  |  |  | 23 |  |  |  | 24 |
Prior service cost |  |  | (5 | ) |  |  | (5 | ) |  |  | (15 | ) |  |  | (12 | )
Net periodic OBEB cost |  | $ | 12 |  |  | $ | 14 |  |  | $ | 36 |  |  | $ | 48 |
Regulatory adjustment1 |  |  | — |  |  |  | (1 | ) |  |  | — |  |  |  | 5 |
Net periodic OPEB cost after regulatory adjustment |  | $ | 12 |  |  | $ | 13 |  |  | $ | 36 |  |  | $ | 53 |
Consumers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net periodic OPEB cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Service cost |  | $ | 7 |  |  | $ | 6 |  |  | $ | 20 |  |  | $ | 19 |
Interest expense |  |  | 19 |  |  |  | 19 |  |  |  | 56 |  |  |  | 59 |
Expected return on plan assets |  |  | (15 | ) |  |  | (14 | ) |  |  | (46 | ) |  |  | (42 | )
Amortization of: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net loss |  |  | 7 |  |  |  | 8 |  |  |  | 23 |  |  |  | 24 |
Prior service cost |  |  | (5 | ) |  |  | (5 | ) |  |  | (15 | ) |  |  | (11 | )
Net periodic OPEB cost |  | $ | 13 |  |  | $ | 14 |  |  | $ | 38 |  |  | $ | 49 |
Regulatory adjustment1 |  |  | — |  |  |  | (1 | ) |  |  | — |  |  |  | 5 |
Net periodic OPEB cost after regulatory adjustment |  | $ | 13 |  |  | $ | 13 |  |  | $ | 38 |  |  | $ | 54 |
1 Regulatory adjustments are the differences between amounts included in rates and the periodic benefit cost calculated. These regulatory adjustments were offset by surcharge revenues, resulting in no impact to net income for the periods presented.
Other Postretirement Benefit Plans, Defined Benefit [Member] |
Schedule of Net Benefit Costs |
In Millions |
|  | OPEB |
|  | Three Months Ended |  |  | Nine Months Ended |
September 30 |  | 2011 |  |  | 2010 |  |  | 2011 |  |  | 2010 |
CMS Energy, including Consumers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net periodic OPEB cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Service cost |  | $ | 7 |  |  | $ | 7 |  |  | $ | 20 |  |  | $ | 20 |
Interest expense |  |  | 20 |  |  |  | 20 |  |  |  | 58 |  |  |  | 61 |
Expected return on plan assets |  |  | (17 | ) |  |  | (16 | ) |  |  | (50 | ) |  |  | (45 | )
Amortization of: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net loss |  |  | 7 |  |  |  | 8 |  |  |  | 23 |  |  |  | 24 |
Prior service cost |  |  | (5 | ) |  |  | (5 | ) |  |  | (15 | ) |  |  | (12 | )
Net periodic OBEB cost |  | $ | 12 |  |  | $ | 14 |  |  | $ | 36 |  |  | $ | 48 |
Regulatory adjustment1 |  |  | — |  |  |  | (1 | ) |  |  | — |  |  |  | 5 |
Net periodic OPEB cost after regulatory adjustment |  | $ | 12 |  |  | $ | 13 |  |  | $ | 36 |  |  | $ | 53 |
Consumers |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net periodic OPEB cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Service cost |  | $ | 7 |  |  | $ | 6 |  |  | $ | 20 |  |  | $ | 19 |
Interest expense |  |  | 19 |  |  |  | 19 |  |  |  | 56 |  |  |  | 59 |
Expected return on plan assets |  |  | (15 | ) |  |  | (14 | ) |  |  | (46 | ) |  |  | (42 | )
Amortization of: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net loss |  |  | 7 |  |  |  | 8 |  |  |  | 23 |  |  |  | 24 |
Prior service cost |  |  | (5 | ) |  |  | (5 | ) |  |  | (15 | ) |  |  | (11 | )
Net periodic OPEB cost |  | $ | 13 |  |  | $ | 14 |  |  | $ | 38 |  |  | $ | 49 |
Regulatory adjustment1 |  |  | — |  |  |  | (1 | ) |  |  | — |  |  |  | 5 |
Net periodic OPEB cost after regulatory adjustment |  | $ | 13 |  |  | $ | 13 |  |  | $ | 38 |  |  | $ | 54 |
1 |  | Regulatory adjustments are the differences between amounts included in rates and the periodic benefit cost calculated. These regulatory adjustments were offset by surcharge revenues, resulting in no impact to net income for the periods presented.

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- Definition Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Topic 715 -SubTopic 20 -Publisher FASB -Number -Article -Subparagraph (h) -Name Accounting Standards Codification -Paragraph 1 -Section 50 -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 + Details
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