DEBT (Details) $ / shares in Units, $ in Millions		1 Months Ended		3 Months Ended			9 Months Ended
	Aug. 21, 2015 $ / shares	Jul. 31, 2015 USD ($)	Jun. 30, 2013 $ / shares	Sep. 30, 2015 USD ($) $ / shares	Sep. 30, 2014 USD ($) $ / shares	Jun. 30, 2013 $ / shares	Sep. 30, 2015 USD ($) item $ / shares	Sep. 30, 2014 USD ($) $ / shares	Dec. 31, 2014 USD ($)
Components of debt
Less: Current portion				$ 108.2			$ 108.2
Total long-term debt				297.1			297.1		$ 450.5
Other Disclosures
Interest Expense				$ 8.0	$ 7.6		22.5	$ 25.9
Debt issuance cost							$ 4.1
Dividends paid (per share) | $ / shares	$ 0.09			$ 0.09	$ 0.08	$ 0.07	$ 0.26	$ 0.23
Repayments of Long-term Debt							$ 380.3	$ 98.9
Loss on extinguishment of debt				$ 36.3			36.3
Carrying value
Components of debt
Total				405.3			405.3		450.5
Less: Current portion				108.2			108.2
Total long-term debt				297.1			297.1		450.5
Fair Value
Components of debt
Total				461.1			461.1		558.0
Less: Current portion				154.5			154.5
Total long-term debt				$ 306.6			$ 306.6		558.0
4.875% Senior Notes due 2025
Components of debt
Interest rate (as a percent)		4.875%		4.875%			4.875%
Other Disclosures
Face value of debt issued		$ 300.0
Debt issuance cost		$ 2.6
Term of debt		10 years
Unamortized discount				$ 2.9			$ 2.9
4.875% Senior Notes due 2025 | Carrying value
Components of debt
Total				297.1			297.1
4.875% Senior Notes due 2025 | Fair Value
Components of debt
Total				$ 306.6			$ 306.6
0.750% Convertible Senior Notes due 2018
Components of debt
Interest rate (as a percent)				0.75%			0.75%
Other Disclosures
Conversion rate, shares per $1,000 principal amount			92.06	92.55
Adjusted conversion price per share of common stock (in dollars per share) | $ / shares			$ 10.86	$ 10.80		10.86	$ 10.80
Percentage of the conversion price that the last reported sales price of the entity's common stock must equal or exceed as per conversion eligibility terms							130.00%
Dividends paid (per share) | $ / shares	$ 0.09					0.07
Number of trading days within 30 consecutive trading days required per the conversion eligibility terms, minimum | item							20
Number of consecutive trading days required per the conversion eligibility terms							30 days
Increased conversion price per share of common stock (in dollars per share) | $ / shares			$ 12.60	$ 12.53		$ 12.60	$ 12.53
0.750% Convertible Senior Notes due 2018 | Carrying value
Components of debt
Total				$ 108.2			$ 108.2		106.0
0.750% Convertible Senior Notes due 2018 | Fair Value
Components of debt
Total				$ 154.5			$ 154.5		$ 177.2
6.700% Senior Notes due 2017
Components of debt
Interest rate (as a percent)				6.70%			6.70%		6.70%
Other Disclosures
Loss on extinguishment of debt				$ 36.3
6.700% Senior Notes due 2017 | Carrying value
Components of debt
Total									$ 344.5
6.700% Senior Notes due 2017 | Fair Value
Components of debt
Total									$ 380.8
Credit Facility
Other Disclosures
Credit facility, maximum borrowing capacity				200.0			$ 200.0
Credit facility covenant terms, financing leverage ratio, maximum							3.00
Credit facility covenant terms, interest coverage ratio, minimum							4.00
Borrowings under the Credit Facility				$ 0.0			$ 0.0