Regulatory Matters (Schedule of GCR Reconciliation Filing Pending with the MPSC) (Details) (USD $) In Millions | 3 Months Ended | 9 Months Ended | 12 Months Ended | 3 Months Ended | 9 Months Ended | |||||
|---|---|---|---|---|---|---|---|---|---|---|
Sep. 30, 2011 | Sep. 30, 2010 | Sep. 30, 2011 | Sep. 30, 2010 | Mar. 31, 2011
Gas Cost Recover (GCR) [Member]
Consumers Energy Company [Member] | Mar. 31, 2010
Gas Cost Recover (GCR) [Member]
Consumers Energy Company [Member] | Sep. 30, 2011
Consumers Energy Company [Member] | Sep. 30, 2010
Consumers Energy Company [Member] | Sep. 30, 2011
Consumers Energy Company [Member] | Sep. 30, 2010
Consumers Energy Company [Member] | |
| Date Of Filing | June 2011 | June 2010 | ||||||||
| Net Over/(Under) Recovery, Including Interest, Requested by Consumers | $ 6 | $ 1 | ||||||||
| Cost of gas sold | $ 107 | $ 104 | $ 1,095 | $ 1,060 | $ 1,200 | $ 1,300 | $ 88 | $ 92 | $ 1,038 | $ 1,001 |