SHORT-TERM DEBT AND LINES OF CREDIT OUTSTANDING (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 30, 2013
Short-term borrowings
Short-term borrowings outstanding	$ 317.6	$ 326.0
Commercial paper
Short-term borrowings
Short-term borrowings outstanding	317.6	326.0	482.4
Average interest rate on amount outstanding at December 31 (as a percent)	0.36%	0.22%	0.40%
Average amount of short-term borrowings outstanding	283.0	378.4	326.3
Short-term notes payable
Short-term borrowings
Short-term borrowings outstanding				200.0
Average amount of short-term borrowings outstanding	$ 0	$ 130.4	$ 0