NET INCOME PER SHARE - Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Basic net income per share:
Net income	$ 10,835	$ 12,755	$ 17,230	$ 26,173
Weighted average common shares outstanding, basic (in shares)	76,213	74,392	75,487	74,074
Net income per share - basic (in dollars per share)	$ 0.14	$ 0.17	$ 0.23	$ 0.35
Diluted net income per share:
Net income	$ 10,835	$ 12,755	$ 17,230	$ 26,173
Weighted average common shares outstanding, basic (in shares)	76,213	74,392	75,487	74,074
Effect of dilutive securities:
2016 Convertible notes (in shares)	0	2,285	0	1,796
Warrants (in shares)	1,589	911	1,864	454
Stock options and restricted stock (in shares)	1,161	1,122	1,352	1,218
Weighted average common shares for diluted earnings per share (in shares)	78,963	78,710	78,703	77,542
Net income per share - diluted (in dollars per share)	$ 0.14	$ 0.16	$ 0.22	$ 0.34