NET INCOME PER SHARE - Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Basic net income per share:
Net income	$ 6,394	$ 13,419
Weighted average common shares outstanding, basic (in shares)	74,765	73,934
Net income per share - basic (in dollars per share)	$ 0.09	$ 0.18
Diluted net income per share:
Net income	$ 6,394	$ 13,419
Weighted average common shares outstanding, basic (in shares)	74,765	73,934
Effect of dilutive securities:
2016 Convertible notes (in shares)	0	1,306
Warrants (in shares)	2,139	0
Stock options and restricted stock (in shares)	1,490	1,226
Weighted average common shares for diluted earnings per share (in shares)	78,394	76,466
Net income per share - diluted (in dollars per share)	$ 0.08	$ 0.18