SHORT-TERM DEBT AND LINES OF CREDIT - REVOLVING CREDIT FACILITIES (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Short-term borrowings
Total short-term credit capacity	$ 250.0	$ 250.0
Short-term borrowings outstanding	18.2	25.6
Available capacity under existing agreements	231.8	224.4
Revolving credit facility maturing on May 17, 2014
Short-term borrowings
Total short-term credit capacity	135.0	135.0
Revolving credit facility maturing on June 13, 2017
Short-term borrowings
Total short-term credit capacity	115.0	115.0
Commercial paper
Short-term borrowings
Short-term borrowings outstanding	$ 18.2	$ 25.6