Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year		$ 295	$ 456	$ 309
Charged to costs and expenses				159
Deductions/ net charge-offs	[1]		(161)	(12)
Balance at end of year		295	295	456
Valuation Allowance for Deferred Income Taxes [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year		2,298	2,465	1,553
Charged to costs and expenses				912
Deductions/ net charge-offs	[1]	(193)	(167)
Balance at end of year		$ 2,105	$ 2,298	$ 2,465

[1] Credits to the allowance for doubtful accounts represent the write-off of bad debts net of recoveries. Credits to the valuation allowance for deferred income taxes represent adjustments to existing valuation allowances.