STOCK PLANS - RSU Activity (Details) - RSUs - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Units
Unvested balance at the beginning of the period (in shares)	957,453	631,141	577,964
Granted (in shares)	446,450	665,476	305,418
Vested (in shares)	(309,779)	(239,085)	(192,760)
Forfeited (in shares)	(138,847)	(100,079)	(59,481)
Unvested balance at the end of the period (in shares)	955,277	957,453	631,141
Weighted Average Grant Date Fair Value (Per Share)
Unvested balance at the beginning of the period (in dollars per shares)	$ 46.34	$ 41.87	$ 42.14
Granted (in dollars per share)	60.81	48.70	43.56
Vested (in dollars per share)	45.16	41.91	45.55
Forfeited (in dollars per share)	50.67	44.43	41.22
Unvested balance at the end of the period (in dollars per shares)	$ 52.85	$ 46.34	$ 41.87
Aggregate Intrinsic Value (in Thousands)
Unvested balance at the end of the period	$ 57,479	$ 57,294	$ 28,591	$ 24,864