Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net income	$ 21,220	$ 17,934	$ 22,943
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,395	5,416	4,324
Stock-based compensation	3,022	2,642	2,349
Fair value adjustments to contingent consideration obligations	182	171	(29)
Provision for doubtful accounts and allowances	293	388	264
Provision for inventory write-downs	1,523	747	671
Provision (benefit) for deferred income taxes	(328)	824	(2,152)
Gains on sale of building, acquisitions and divestitures	(470)	0	(7,474)
Foreign currency transaction gain	100	(57)	259
Changes in operating assets and liabilities:
Accounts receivable	(939)	(1,301)	(1,283)
Inventory and other deferred costs	(2,609)	(11,335)	(4,262)
Prepaid expenses and other assets	89	(654)	(418)
Accounts payable and other liabilities	4,322	(596)	4,314
Net cash provided by operating activities	34,800	14,179	19,506
Investing activities
Purchases of property and equipment	(2,982)	(3,761)	(3,054)
Proceeds from sale of building	2,023	0	0
Payments related to acquisitions	(72,627)	(21,240)	(12,282)
Purchases of short-term marketable securities	(2,205)	(22,699)	(19,619)
Proceeds from sales of marketable securities	22,900	23,600	20,500
Proceeds from divestitures	0	0	7,400
Net cash used in investing activities	(52,891)	(24,100)	(7,055)
Financing activities
Payment of deferred acquisition consideration	(2,800)	(2,059)	(1,199)
Proceeds from revolving line of credit	25,000	0	0
Proceeds from issuance of long-term debt	40,000	0	0
Payments of revolving line of credit	(25,000)	0	0
Payments of long-term debt	(1,000)	0	0
Payment of deferred debt issuance costs	(1,751)	0	0
Proceeds from issuance of common stock	5,971	4,856	2,969
Purchase of treasury stock	(570)	(683)	(741)
Common stock cash dividend paid	(7,695)	(6,736)	(5,445)
Net cash provided by (used in) financing activities	32,155	(4,622)	(4,416)
Effect of exchange rate changes on cash and cash equivalents	914	11	(813)
Net increase (decrease) in cash and cash equivalents	14,978	(14,532)	7,222
Cash and cash equivalents at beginning of year	11,786	26,318	19,096
Cash and cash equivalents at end of year	$ 26,764	$ 11,786	$ 26,318