EARNINGS PER SHARE (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Sep. 30, 2016
Numerator:
Net income (loss)	$ 1,704	$ (53,675)	$ (2,206)	$ (53,900)
Number of shares outstanding, end of period:
Unvested restricted stock (in shares)	(38)	(88)	(38)	(88)
Effect of weighted average shares outstanding (in shares)	(54)	(131)	(199)	(244)
Basic weighted average common share outstanding (in shares)	42,661	41,811	42,516	41,698
Dilutive effect of stock options and other stock awards (in shares)	1,255	0	0	0
Diluted weighted average shares outstanding (in shares)	43,916	41,811	42,516	41,698
Antidilutive potentially issuable shares (in shares)	0	2,586	2,105	2,586
Class A Common Stock
Number of shares outstanding, end of period:
Common stock, outstanding shares (in shares)	41,765	41,042	41,765	41,042	41,298	41,042
Class B Common Stock
Number of shares outstanding, end of period:
Common stock, outstanding shares (in shares)	988	988	988	988	988	988