SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable Reserves
Balance at beginning of period	$ 817	$ 1,289	$ 1,243
Charged to cost and expenses	1,030	1,130	1,126
Write-offs, Exchange Rate Fluctuations and Other Items	(404)	(1,602)	(1,080)
Balance at end of period	1,443	817	1,289
Valuation Allowance Of Deferred Tax Assets [Member]
Balance at beginning of period	10,237	8,586	8,962
Net additions charged to income (expense)	4,768	2,174	(138)
Write-offs, Exchange Rate Fluctuations and Other Items	(489)	(523)	(238)
Balance at end of period	$ 14,516	$ 10,237	$ 8,586