INCOME TAXES - Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 5,178	$ (33)	$ 25
State	1,289	139	90
Total current	6,467	106	115
Deferred:
Federal	(295,466)	19,980	17,042
State	31,915	(5,292)	1,280
Total deferred	(263,551)	14,688	18,322
Income taxes (benefit)	$ (257,085)	$ 14,794	$ 18,437