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	$ 145.1	$ 25.6
Commercial paper
Short-term borrowings
Short-term borrowings outstanding	145.1	25.6	95.4
Average interest rate (as a percent)	0.32%	0.14%	0.24%
Average amount of short-term borrowings outstanding	43.3	80.8	150.2
Short-term notes payable
Short-term borrowings
Short-term borrowings outstanding	0	0	0	200.0
Average amount of short-term borrowings outstanding	$ 0	$ 130.4	$ 0