Changes in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Allowance For Doubtful Accounts Receivable Rollforward
Balance at beginning of year	$ 274	$ 297	$ 321
Addition to credit loss expense	121	158	33
Credit loss resulting from acquisitions	216		120
Write-offs, net of recoveries of amounts previously reserved	(45)	(207)	(179)
Exchange rate changes	(10)	26	2
Balance at end of year	$ 556	$ 274	$ 297