Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating activities:
Consolidated net income	$ 11,251	$ 4,990
Adjustments to reconcile consolidated net income to net cash provided by operating activities:
Depreciation and amortization	4,199	3,296
Stock-based compensation expense	2,817	1,994
Increase (decrease) in long-term deferred revenue	2,038	(81)
Increase in other assets	33	62
Increase in long-term income taxes payable	7	5
Deferred income taxes	0	2
Credit gain on available-for-sale securities	0	(1)
Change in current assets and liabilities, net	(10,232)	(5,682)
Net cash provided by operating activities	10,113	4,585
Investing activities:
Sales or maturities of short-term investments	0	25,000
Additions to property, plant and equipment	(10,089)	(22,683)
Net cash (used for) provided by investing activities	(10,089)	2,317
Financing activities:
Proceeds from employee stock plans	2,261	1,810
Net cash provided by financing activities	2,261	1,810
Effect of foreign exchange rates on cash	1	(80)
Net increase in cash and cash equivalents	2,286	8,632
Cash and cash equivalents at beginning of period	190,611	182,418
Cash and cash equivalents at end of period	$ 192,897	$ 191,050