EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Net income	$ 53,882	$ 38,935	$ 103,105	$ 105,025
Denominator:
Weighted average basic shares (in shares)	52,863	31,800	48,381	31,599
Dilutive potential common shares (in shares)	191	548	287	663
Weighted average fully diluted shares (in shares)	53,054	32,348	48,668	32,262
Earnings per share:
Basic (in dollars per share)	$ 1.02	$ 1.22	$ 2.13	$ 3.32
Diluted (in dollars per share)	$ 1.02	$ 1.20	$ 2.12	$ 3.26
Outstanding common stock equivalents having no dilutive effect (in shares)	1	11	1	16