CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities:
Net income	$ 17,847	$ 16,651
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,866	6,210
Deferred income taxes	(535)	1,092
Stock-based compensation	1,321	1,338
Net change in unrealized gains and losses on investments	475	(1,024)
Net change in accrued interest, premiums, and discounts on investments	202	269
Other	0	25
Other Operating	26,176	24,561
Changes in operating assets and liabilities:
Accounts receivable	(6,516)	(6,237)
Inventories	(3,503)	2,573
Prepaid expenses	(2,201)	(4,006)
Other non-current assets	573	12
Accounts payable and accrued liabilities	2,165	(1,454)
Accrued income and other taxes	1,141	234
Other non-current liabilities	502	345
Cash flows from operating activities	18,337	16,028
Cash flows from investing activities:
Property, plant and equipment additions	(15,247)	(7,252)
Purchase of investments	(22,322)	(16,110)
Proceeds from sale of investments	208	166
Proceeds from maturities of investments	19,978	19,246
Cash flows from investing activities	(17,383)	(3,950)
Cash flows from financing activities:
Purchase of treasury stock	(9,340)	(10,488)
Shares tendered for employees' withholding taxes on stock-based compensation	(454)	(585)
Dividends paid	(6,987)	(6,385)
Cash flows from financing activities	(16,781)	(17,458)
Net change in cash and cash equivalents	(15,827)	(5,380)
Cash and cash equivalents at beginning of period	32,264	22,450
Cash and cash equivalents at end of period	16,437	17,070
Cash paid for:
Income taxes	3,952	5,095
Non-cash financing activities:
Non-cash effect of stock option exercises	$ 4,008	$ 6,012