EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator for basic and diluted earnings per share:
Net income	$ 66,624	$ 85,565	$ 58,777	$ 60,754	$ 152,189	$ 119,531
Numerator for basic and diluted earnings per share	$ 66,624		$ 58,777		$ 152,189	$ 119,531
Denominator:
Weighted average common shares for basic earnings per share	55,700,706		54,681,959		55,493,727	54,464,753
Net effect of dilutive stock options, restricted stock units and restricted stock awards	2,545,525		2,932,325		2,700,674	2,961,810
Weighted average common shares for diluted earnings per share	58,246,231		57,614,284		58,194,401	57,426,563
Net income per share:
Basic (in dollars per share)	$ 1.20		$ 1.07		$ 2.74	$ 2.19
Diluted (in dollars per share)	$ 1.14		$ 1.02		$ 2.62	$ 2.08
Anti-dilutive options not included in the calculation (in shares)	146,732		168,451		77,925	97,327