BASIS OF PRESENTATION (Details) - Reclassification - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2014
Income statement
Reclassifications
Reclassification from taxes other than income taxes to operating and maintenance expense	$ 7.0	$ 16.4
Reclassification from cost of sales to operating and maintenance expense	$ 3.4	$ 7.1
Balance sheet
Reclassifications
Reclassification from current regulatory assets to accounts receivable			$ 47.2
Reclassification from current regulatory assets to long-term regulatory assets			71.7
Reclassification from equity method investments to other long-term assets			13.9
Reclassification from current regulatory liabilities to energy costs refundable through rate adjustments			44.8
Reclassification from current regulatory liabilities to long-term regulatory liabilities			$ 108.9