DEBT - 1.00 CONVERTIBLE NOTES (Details) - Convertible Debt - 1.00% Convertible Notes due 2018 $ / shares in Units, label in Thousands	Jul. 17, 2013 USD ($)	Jun. 18, 2013 USD ($) label $ / shares
Convertible Notes
Principal amount at issuance		$ 250,000,000
Interest rate		1.00%
Percentage of par value at which debt was issued		98.50%
Proceeds from issuance of debt	$ 283,188,000	$ 246,250,000
Period of overallotment option to purchase additional amount of debt granted to underwriters		30 days
Amount pertaining to exercise of over-allotment of debt by underwriters	$ 37,500,000
Initial conversion rate of common stock per $1000 of principal amount of Convertible Notes (in shares)		46.4727
Principal amount used for debt instrument conversion ratio		$ 1,000
Initial conversion price of convertible notes into common stock (in dollars per share) | $ / shares		$ 21.52
Number of shares to be converted into common stock | label		13,361
Maximum
Convertible Notes
Additional amount of debt for purchase of which overallotment option is granted to underwriters		$ 37,500,000