NET INCOME (LOSS) PER SHARE - Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net income (loss)	$ 41,980	$ 145,523	$ (11,016)
Denominator:
Weighted average common shares outstanding - basic (in shares)	44,262,000	42,671,000	41,513,000
Computation of diluted securities:
Weighted average number of shares outstanding - diluted (in shares)	45,630,000	43,682,000	41,513,000
Net income (loss) per share:
Basic net income (loss) per common share (in USD per share)	$ 0.95	$ 3.41	$ (0.27)
Diluted net income (loss) per common share (in USD per share)	$ 0.92	$ 3.33	$ (0.27)
Stock options
Computation of diluted securities:
Dilutive effect of diluted securities (in shares)	1,030,000	783,000	0
RSUs
Computation of diluted securities:
Dilutive effect of diluted securities (in shares)	298,000	227,000	0
Conversion Premium on 2022 Notes
Computation of diluted securities:
Dilutive effect of conversion premium on the 2022 Notes (in shares)	38,000
ESPP
Computation of diluted securities:
Dilutive effect of diluted securities (in shares)	2,000	1,000	0