NET INCOME (LOSS) PER SHARE (Basic and Diluted Net Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Basic net income per share:
Net income	$ 25,138	$ 13,295	$ 11,376	$ 10,992	$ 44,355	$ 3,159	$ 10,835	$ 6,394	$ 60,801	$ 64,743	$ 74,564
Weighted average common shares outstanding, basic (in shares)									82,857	76,897	74,386
Per Share-Basic (in dollars per share)	$ 0.29	$ 0.16	$ 0.14	$ 0.14	$ 0.57	$ 0.04	$ 0.14	$ 0.09	$ 0.73	$ 0.84	$ 1.00
Diluted net income per share:
Net income	$ 25,138	$ 13,295	$ 11,376	$ 10,992	$ 44,355	$ 3,159	$ 10,835	$ 6,394	$ 60,801	$ 64,743	$ 74,564
Weighted average common shares outstanding, basic (in shares)									82,857	76,897	74,386
Effect of dilutive securities:
2016 Convertible notes (in shares)									0	0	2,296
Warrants (in shares)									0	971	1,166
Stock options and restricted stock (in shares)									1,142	1,253	1,346
Weighted average common shares for diluted earnings per share (in shares)									83,999	79,121	79,194
Per Share-Diluted (in dollars per share)	$ 0.29	$ 0.15	$ 0.14	$ 0.14	$ 0.56	$ 0.04	$ 0.14	$ 0.08	$ 0.72	$ 0.82	$ 0.94