STOCK-BASED COMPENSATION (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Stock based compensation
Total stock-based compensation expense	$ 1.9	$ 1.5
Deferred Income tax benefit	0.8	0.6
Amount of stock-based compensation cost capitalized	0	0
Stock options
Stock based compensation
Total stock-based compensation expense	0.1	0.2
Performance stock rights
Stock based compensation
Total stock-based compensation expense	0.8	0.5
Restricted share units
Stock based compensation
Total stock-based compensation expense	$ 1.0	$ 0.8