Annual report pursuant to Section 13 and 15(d)

LONG-TERM DEBT (Schedule of Debt Interest Expense) (Details)

v3.3.1.900
LONG-TERM DEBT (Schedule of Debt Interest Expense) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Jul. 31, 2014
May. 31, 2014
2.5% Convertible Senior Notes Due 2019 [Member]          
Debt Instrument [Line Items]          
Interest rate, stated percentage 2.50%       2.50%
Contractual interest coupon $ 6,856        
Amortization of debt discount 4,599        
Amortization of debt issuance costs 1,355        
Total interest cost recognized on the notes $ 12,810        
2.5% Convertible Senior Notes & 2.875% Convertible Senior Notes [Member]          
Debt Instrument [Line Items]          
Contractual interest coupon   $ 8,701      
Amortization of debt discount   10,165      
Amortization of debt issuance costs   1,175      
Total interest cost recognized on the notes   $ 20,041      
2.875% Convertible Senior Notes Due 2027 [Member]          
Debt Instrument [Line Items]          
Interest rate, stated percentage 2.875%     2.875%  
Contractual interest coupon     $ 6,325    
Amortization of debt discount     12,995    
Amortization of debt issuance costs     703    
Total interest cost recognized on the notes     $ 20,023