EARNINGS PER SHARE (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Computation of Basic Income per Share [Abstract]
Net income	$ 40.5	$ 38.7
Basic shares (in shares)	80.2	80.1
Basic net income per share (in dollars per share)	$ 0.50	$ 0.48
Computation of Diluted Income per Share [Abstract]
Basic shares (in shares)	80.2	80.1
Stock-based compensation (in shares)	1.0	0.8
Diluted shares (in shares)	81.2	80.9
Diluted net income per share (in dollars per share)	$ 0.50	$ 0.48
Antidilutive shares excluded from the computation of earnings per share (in shares)	1.4	0.8