DEBT (Details) (USD $)	0 Months Ended	12 Months Ended
	Sep. 09, 2014	Dec. 31, 2014	Sep. 30, 2014
Long-term debt
Effective interest rate (as a percent)			10.00%
Carrying amounts of the liability component
Net carrying amount of the liability component		$ 229,891,000
Interest expense incurred
Unamortized debt discount and debt issuance costs included in senior convertible notes		115,100,000
Unamortized debt discount and debt issuance costs included in other assets		6,700,000
Unamortized debt discount and debt issuance costs		121,800,000
Convertible Debt
Long-term debt
Aggregate principal amount of notes issued	345,000,000	345,000,000
Net proceeds from debt offering	334,200,000
Underwriting discount	10,400,000
Offering expenses	400,000
Interest rate (as a percent)	2.50%	2.50%
Conversion rate of common stock per $1,000 principal amount	51.9852
Conversion price of common stock (in dollars per share)	$ 19.24
Redeemable principal amount of debt (as a percent)	100.00%
Effective interest rate (as a percent)	9.34%
Liability component of debt	230,000,000
Equity component of debt	115,100,000
Debt issuance costs	7,100,000
Equity issuance costs	3,700,000
Net deferred tax liability	41,900,000
Carrying amounts of the liability component
Net carrying amount of the liability component		229,891,000
Unamortized discount of the liability component		115,109,000
Principal amount of the 2021 Notes		345,000,000
Interest expense incurred
Stated coupon interest		2,683,000
Amortization of debt discount and debt issuance costs		4,200,000
Total interest expense		$ 6,883,000