Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Operating activities:
Consolidated net income	$ 28,353	$ 15,570
Adjustments to reconcile consolidated net income to net cash provided by operating activities:
Depreciation and amortization	8,648	6,665
Stock-based compensation expense	5,829	4,616
Increase (decrease) in long-term deferred revenue	1,616	(143)
(Decrease) increase in other assets	(103)	133
Provision for doubtful accounts	43	0
Increase in long-term income taxes payable	13	8
Deferred income taxes	(63)	(58)
Credit gain on available-for-sale securities	0	(2)
Change in current assets and liabilities, net	(15,183)	(11,381)
Net cash provided by operating activities	29,153	15,408
Investing activities:
Sales or maturities of short-term investments	0	25,000
Additions to property, plant and equipment	(18,627)	(36,878)
Net cash used for investing activities	(18,627)	(11,878)
Financing activities:
Proceeds from employee stock plans	2,722	1,974
Net cash provided by financing activities	2,722	1,974
Effect of foreign exchange rates on cash	(30)	(245)
Net increase in cash and cash equivalents	13,218	5,259
Cash and cash equivalents at beginning of period	190,611	182,418
Cash and cash equivalents at end of period	$ 203,829	$ 187,677