LONG-TERM DEBT, DERIVATIVES AND LETTERS OF CREDIT - Components of Convertible Debt Interest Expense (Details) - USD ($) $ in Thousands	7 Months Ended		12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 31, 2015
Debt Instrument [Line Items]
Amortization of debt discount and issuance costs	$ 256		$ 3,085	$ 541		$ 223
Total interest expense	$ 4,898	$ 1,332	21,487	$ 12,667	$ 5,792	$ 2,489
Convertible Debt
Debt Instrument [Line Items]
Coupon interest			4,823
Amortization of debt discount and issuance costs			2,310
Total interest expense			$ 7,133
Effective interest rate			9.12%