RISK MANAGEMENT ACTIVITIES - UTILITY SEGMENTS, NOTIONAL VOLUMES (Details) (Non-hedge derivatives, Utility segments)	9 Months Ended	12 Months Ended
	Sep. 30, 2014 MMBTU	Dec. 31, 2013 MMBTU
Natural gas contracts | Purchases
Risk management activities
Notional volume of outstanding derivative contracts (mmbtu or kwh)	236,710,000	312,480,000
Natural gas contracts | Sales
Risk management activities
Notional volume of outstanding derivative contracts (mmbtu or kwh)	190,000	2,930,000
FTRs | Other transactions
Risk management activities
Notional volume of outstanding derivative contracts (mmbtu or kwh)	5,644,000,000	3,633,100,000
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)	3,400,000	4,800,000
Coal contracts | Sales
Risk management activities
Notional volume of outstanding derivative contracts (tons)	0	0