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DEBT (Details 2) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Interest Expense, Debt [Abstract]      
Amortization of debt discount $ 10,423 $ 4,088 $ 4,102
Interest Costs Capitalized 1,100 1,500 800
Notes      
Interest Expense, Debt [Abstract]      
Contractual interest expense 7,344 3,852 3,856
Amortization of debt issuance costs 1,381 612 615
Amortization of debt discount 10,423 4,088 4,102
Interest Costs Capitalized (1,101) (1,491) (848)
Total interest expense recognized $ 18,047 $ 7,061 $ 7,725
Effective interest rate (as a percent) 7.77% 7.22% 7.21%