CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING ACTIVITIES:
Net (loss) income	$ (62,147,000)	$ 4,930,000	$ (14,516,000)
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	18,516,000	18,313,000	16,588,000
Compensation for stock options and restricted stock units	11,071,000	7,620,000	6,450,000
Provision for bad debts	2,090,000	907,000	370,000
Loss on disposal of assets	2,639,000	192,000	451,000
Provision for excess and obsolete inventory	16,886,000	5,757,000	1,734,000
Impairment of goodwill	21,233,000	0	0
Impairment of acquired intangibles	10,548,000	0	0
Impairment of loan to affiliate	549,000	0	0
Deferred income tax (benefit) expense	(6,304,000)	689,000	(1,740,000)
(Increase) decrease in:
Accounts receivable, net	10,406,000	(15,995,000)	(6,766,000)
Inventories	(4,136,000)	(20,532,000)	(10,926,000)
Prepaid expenses and other assets	1,188,000	(11,310,000)	(253,000)
Increase (decrease) in:
Accounts payable and accrued liabilities	(2,518,000)	11,195,000	1,103,000
Income taxes payable	1,041,000	(3,286,000)	20,011,000
Net cash provided by operating activities	32,468,000	6,323,000	10,355,000
INVESTING ACTIVITIES:
Purchases of investments	(50,000,000)	(47,000,000)	(33,000,000)
Proceeds from sale of investments	50,000,000	33,000,000	65,000,000
Purchases of property and equipment	(6,675,000)	(11,021,000)	(8,970,000)
Payments for internally capitalized patents	(2,118,000)	(1,900,000)	(2,377,000)
Acquisition of business, net of cash received	0	(27,067,000)	(5,596,000)
Other	(549,000)	(1,786,000)	0
Net cash (used in) provided by investing activities	(9,342,000)	(55,774,000)	15,057,000
FINANCING ACTIVITIES:
Payments on capital leases	(358,000)	(157,000)	(108,000)
Payments of contingent consideration for acquisitions	(3,101,000)	(888,000)	(521,000)
Payments for taxes related to net share settlement of equity awards	(2,199,000)	0	0
Proceeds from issuance of stock related to stock option exercises	7,901,000	20,855,000	3,594,000
Net cash provided by financing activities	2,243,000	19,810,000	2,965,000
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	(518,000)	(2,536,000)	6,414,000
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	24,851,000	(32,177,000)	34,791,000
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	108,783,000	140,960,000	106,169,000
CASH AND CASH EQUIVALENTS, END OF YEAR	133,634,000	108,783,000	140,960,000
Customer deposits
Increase (decrease) in:
Increase (decrease) in contract with customer, liability	(30,000)	513,000	(461,000)
Unearned service revenues
Increase (decrease) in:
Increase (decrease) in contract with customer, liability	$ 11,436,000	$ 7,330,000	$ (1,690,000)