EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator for basic and diluted earnings per share:
Net income	$ 89,432	$ 66,624	$ 85,565	$ 67,002	$ 58,777	$ 60,754	$ 241,621	$ 186,533
Numerator for basic and diluted earnings per share	$ 89,432			$ 67,002			$ 241,621	$ 186,533
Denominator:
Weighted average common shares for basic earnings per share	55,883,879			54,877,666			55,624,727	54,603,903
Net effect of dilutive stock options, restricted stock units and restricted stock awards	2,732,227			2,966,689			2,716,451	2,963,436
Weighted average common shares for diluted earnings per share	58,616,106			57,844,355			58,341,178	57,567,339
Net income per share:
Basic (in dollars per share)	$ 1.60			$ 1.22			$ 4.34	$ 3.42
Diluted (in dollars per share)	$ 1.53			$ 1.16			$ 4.14	$ 3.24
Anti-dilutive options not included in the calculation (in shares)	2,627			143,617			40,276	112,757