Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities:
Consolidated net income	$ 941	$ 6,862
Adjustments to reconcile consolidated net income to net cash provided by operating activities:
Depreciation and amortization	5,439	4,998
Stock-based compensation expense, net	2,646	1,539
Provision (benefit) for doubtful accounts	23	(117)
Increase (decrease) in long-term income taxes payable	4	(2)
Decrease in long-term deferred revenue	(160)	(36)
Gain on disposal of equipment	(6)	(22)
Deferred income taxes	17	24
Credit gain on available-for-sale securities	(2)	(2)
Change in current assets and liabilities, net	(5,233)	(8,005)
Net cash provided by operating activities	3,669	5,239
Investing activities:
Additions to property, plant and equipment	(8,724)	(5,864)
Proceeds from sale of equipment	6	22
Increase (decrease) in other assets	95	(137)
Net cash used for investing activities	(8,623)	(5,979)
Financing activities:
Proceeds from employee stock plans	7,385	1,707
Proceeds from public offering of stock	109,732
Payment of contingent consideration obligations	(144)	(102)
Net cash provided by financing activities	116,973	1,605
Effect of foreign exchange rates on cash	17	60
Net increase in cash and cash equivalents	112,036	925
Cash and cash equivalents at beginning of year	84,668	70,557
Cash and cash equivalents at end of year	$ 196,704	$ 71,482