NET INCOME PER SHARE - Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Basic net income per share:
Net income	$ 3,159	$ 20,144	$ 20,388	$ 46,316
Weighted average common shares outstanding, basic (in shares)	78,186	74,534	76,387	74,286
Net income per share - basic (in dollars per share)	$ 0.04	$ 0.27	$ 0.27	$ 0.62
Diluted net income per share:
Net income	$ 3,159	$ 20,144	$ 20,388	$ 46,316
Weighted average common shares outstanding, basic (in shares)	78,186	74,534	76,387	74,286
Effect of dilutive securities:
2016 Convertible notes (in shares)	0	3,176	0	2,256
Warrants (in shares)	158	2,012	1,295	974
Stock options and restricted stock (in shares)	1,111	1,310	1,291	1,288
Weighted average common shares for diluted earnings per share (in shares)	79,455	81,032	78,973	78,804
Net income per share - diluted (in dollars per share)	$ 0.04	$ 0.25	$ 0.26	$ 0.59