RISK MANAGEMENT ACTIVITIES - NOTIONAL VOLUMES (Details) (Non-hedge derivatives)	6 Months Ended	12 Months Ended
	Jun. 30, 2014 MMBTU	Dec. 31, 2013 MMBTU
Natural gas contracts | Purchases
Risk management activities
Notional volume of outstanding derivative contracts (mmbtu or kwh)	165,920,000	224,250,000
Natural gas contracts | Sales
Risk management activities
Notional volume of outstanding derivative contracts (mmbtu or kwh)	0	700,000
FTRs | Other Transactions
Risk management activities
Notional volume of outstanding derivative contracts (mmbtu or kwh)	7,891,100,000	3,427,000,000
Petroleum product contracts | Purchases
Risk management activities
Notional volume of outstanding derivative contracts (barrels)	100,000	100,000
Petroleum product contracts | Sales
Risk management activities
Notional volume of outstanding derivative contracts (barrels)	0	0
Coal contracts | Purchases
Risk management activities
Notional volume of outstanding derivative contracts (tons)	4,000,000	4,800,000
Coal contracts | Sales
Risk management activities
Notional volume of outstanding derivative contracts (tons)	0	0