EARNINGS PER SHARE (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Computation of Basic Income per Share [Abstract]
Net income	$ 47.6	$ 42.1	$ 86.3	$ 175.8
Basic shares (in shares)	80.1	80.0	80.1	79.8
Basic net income per share (in dollars per share)	$ 0.59	$ 0.53	$ 1.08	$ 2.20
Computation of Diluted Income per Share [Abstract]
Basic shares (in shares)	80.1	80.0	80.1	79.8
Stock-based compensation (in shares)	0.6	1.1	0.7	0.9
Diluted shares (in shares)	80.7	81.1	80.8	80.7
Diluted net income per share (in dollars per share)	$ 0.59	$ 0.52	$ 1.07	$ 2.18
Antidilutive shares excluded from the computation of earnings per share (in shares)	1.8	0	0.8	0.9