EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator for basic and diluted earnings per share:
Net income	$ 481,652	$ 327,160	$ 261,057
Numerator for basic	481,652	327,160	261,057
Numerator for diluted	$ 481,652	$ 327,160	$ 261,057
Denominator:
Weighted average common shares for basic earnings per share (in shares)	56,511	55,727	54,719
Net effect of dilutive stock options, restricted stock units, restricted stock awards and stock issuable under the ESPP (in shares)	2,553	2,719	2,949
Weighted average common shares for diluted earnings per share	59,064	58,446	57,668
Net Income per share:
Basic (in dollars per share)	$ 8.52	$ 5.87	$ 4.77
Diluted (in dollars per share)	$ 8.15	$ 5.60	$ 4.53
Anti-dilutive stock excluded from the calculation (in shares)	32	40	120