CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SALES
Sales	$ 303,768	$ 381,765	$ 403,627
COST OF SALES
Cost of sales (exclusive of depreciation and amortization, shown separately below)	143,921	183,633	182,074
GROSS PROFIT	159,847	198,132	221,553
OPERATING EXPENSES
Selling, general and administrative	131,827	177,378	169,717
Research and development	42,896	44,175	46,082
Restructuring costs	15,806	0	0
Impairment loss	0	35,213	0
Total operating expenses	190,529	256,766	215,799
(LOSS) INCOME FROM OPERATIONS	(30,682)	(58,634)	5,754
OTHER EXPENSE (INCOME)
Interest income	(340)	(714)	(429)
Other expense, net	431	2,313	1,139
Interest expense	0	781	486
(LOSS) INCOME BEFORE INCOME TAX (BENEFIT) EXPENSE	(30,773)	(61,014)	4,558
INCOME TAX (BENEFIT) EXPENSE	(31,402)	1,133	(372)
NET INCOME (LOSS)	$ 629	$ (62,147)	$ 4,930
NET INCOME (LOSS) PER SHARE - BASIC (in dollars per share)	$ 0.04	$ (3.58)	$ 0.29
NET INCOME (LOSS) PER SHARE - DILUTED (in dollars per share)	$ 0.04	$ (3.58)	$ 0.29
Weighted average shares - Basic (in shares)	17,769,958	17,383,415	17,043,167
Weighted average shares - Diluted (in shares)	17,926,324	17,383,415	17,348,456
Product
SALES
Sales	$ 218,587	$ 289,679	$ 320,584
COST OF SALES
Cost of sales (exclusive of depreciation and amortization, shown separately below)	98,864	133,246	130,876
Service
SALES
Sales	85,181	92,086	83,043
COST OF SALES
Cost of sales (exclusive of depreciation and amortization, shown separately below)	$ 45,057	$ 50,387	$ 51,198