EMPLOYEE BENEFIT PLANS (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Benefits
Net regulatory assets
Net actuarial loss	$ 110.2	$ 252.7
Prior service costs (credits)	2.4	6.0
Total	112.6	258.7
Estimated amounts that will be amortized as a component of net periodic benefit cost during 2014
Net actuarial losses	15.2
Prior service costs (credits)	0.6
Total 2014 - estimated amortization	15.8
Components of net periodic benefit cost (including amounts capitalized to the balance sheets)
Service cost	10.8	12.8	11.3
Interest cost	30.6	34.0	36.1
Expected return on plan assets	(57.2)	(55.4)	(46.8)
Amortization of transition obligation	0	0	0
Amortization of prior service cost (credit)	3.6	4.5	4.8
Amortization of net actuarial loss	24.0	14.9	8.6
Net periodic benefit cost	11.8	10.8	14.0
Other Benefits
Net regulatory assets
Net actuarial loss	11.5	84.6
Prior service costs (credits)	(12.0)	(14.3)
Total	(0.5)	70.3
Estimated amounts that will be amortized as a component of net periodic benefit cost during 2014
Net actuarial losses	2.1
Prior service costs (credits)	(2.2)
Total 2014 - estimated amortization	(0.1)
Components of net periodic benefit cost (including amounts capitalized to the balance sheets)
Service cost	10.6	8.5	7.1
Interest cost	13.4	15.1	15.1
Expected return on plan assets	(14.8)	(14.6)	(14.2)
Amortization of transition obligation	0	0.2	0.2
Amortization of prior service cost (credit)	(2.1)	(3.0)	(3.5)
Amortization of net actuarial loss	7.5	5.7	3.0
Net periodic benefit cost	$ 14.6	$ 11.9	$ 7.7