COMMON EQUITY (Details 3) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Numerator:
Net income from continuing operations	$ 132.3	$ 39.4	$ (3.9)	$ 182.2	$ 69.2	$ 74.3	$ 51.7	$ 98.8	$ 350.0	$ 294.0	$ 230.0
Discontinued operations, net of tax									4.8	(9.7)	0.5
Preferred stock dividends of subsidiary									(3.1)	(3.1)	(3.1)
Noncontrolling interest in subsidiaries									0.1	0.2	0
Net income attributed to common shareholders	131.6	38.1	(5.4)	187.5	68.0	65.7	48.8	98.9	351.8	281.4	227.4
Dilutive Securities, Effect on Basic Earnings Per Share									(0.1)	0	0
Net income (loss) attributed to common shareholders, diluted									$ 351.7	$ 281.4	$ 227.4
Denominator:
Average shares of common stock - basic									79.5	78.6	78.6
Effect of dilutive securities - Stock-based compensation (in shares)									0.4	0.5	0.5
Effect of dilutive securities - Deferred compensation (in shares)									0.2	0.2	0
Average shares of common stock - diluted									80.1	79.3	79.1
Earnings (Loss) per common share
Basic (in dollars per share)	$ 1.64	$ 0.48	$ (0.07)	$ 2.38	$ 0.87	$ 0.84	$ 0.62	$ 1.26	$ 4.43	$ 3.58	$ 2.89
Diluted (in dollars per share)	$ 1.63	$ 0.47	$ (0.07)	$ 2.37	$ 0.86	$ 0.83	$ 0.62	$ 1.25	$ 4.39	$ 3.55	$ 2.87
Disclosure of antidilutive shares
Document Fiscal Year Focus									2013
Stock-based compensation
Disclosure of antidilutive shares
Antidilutive shares excluded from calculation of diluted earnings per share									0.3	0.7	0.7
Deferred compensation
Disclosure of antidilutive shares
Antidilutive shares excluded from calculation of diluted earnings per share									0.1	0	0