STOCK-BASED COMPENSATION (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Stock-based compensation expense and the related deferred tax benefit recognized in income
Total stock-based compensation expense	$ 5.7	$ 4.7
Deferred income tax benefit	2.3	1.9
Amount of stock-based compensation cost capitalized	0	0
Stock Options
Stock-based compensation expense and the related deferred tax benefit recognized in income
Total stock-based compensation expense	0.4	0.4
Performance Stock Rights
Stock-based compensation expense and the related deferred tax benefit recognized in income
Total stock-based compensation expense	2.2	1.2
Restricted Share Units
Stock-based compensation expense and the related deferred tax benefit recognized in income
Total stock-based compensation expense	2.8	2.1
Nonemployee director deferred stock units
Stock-based compensation expense and the related deferred tax benefit recognized in income
Total stock-based compensation expense	$ 0.3	$ 1.0