cm:Concept: us-gaap:IncreaseDecreaseInEnergyTradingActivity
| Increase (Decrease) in Energy Trading Activity |
| us-gaap:IncreaseDecreaseInEnergyTradingActivity |
| The increase (decrease) during the reporting period in the value of long term assets generated by energy trading activities, which involve the purchase and sale of energy under forward contracts at fixed and variable prices and the buying and selling of financial energy contracts which include exchange futures and options and over the counter options and swaps. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:IncreaseDecreaseInEnergyTradingActivity |