Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating activities:
Consolidated net income	$ 15,570	$ 34,478
Adjustments to reconcile consolidated net income to net cash provided by operating activities:
Depreciation and amortization	6,665	5,618
Stock-based compensation expense	4,616	3,138
Decrease in long-term deferred revenue	(143)	(160)
Decrease in contingent consideration obligations	0	(74)
Gain on disposal of equipment	0	106
Increase in other assets	133	37
Increase in long-term income taxes payable	8	6
Deferred income taxes	(58)	5
Credit gain on available-for-sale securities	(2)	(2)
Change in current assets and liabilities, net	(11,381)	(13,037)
Net cash provided by operating activities	15,408	30,115
Investing activities:
Purchases of short-term investments	0	(50,706)
Sales or maturities of short-term investments	25,000	30,000
Additions to property, plant and equipment	(36,878)	(15,782)
Other	0	(106)
Net cash used for investing activities	(11,878)	(36,594)
Financing activities:
Proceeds from employee stock plans	1,974	4,751
Payment of contingent consideration obligations	0	(107)
Net cash provided by financing activities	1,974	4,644
Effect of foreign exchange rates on cash	(245)	(144)
Net increase (decrease) in cash and cash equivalents	5,259	(1,979)
Cash and cash equivalents at beginning of period	182,418	161,742
Cash and cash equivalents at end of period	$ 187,677	$ 159,763