Schedule II - Valuation and Qualifying Accounts (Details) - Accounts receivable allowance [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 251	$ 256	$ 148
Charged/(Credited) to costs and expenses, additions and deductions	167	60	159
Charged to other accounts, additions and deductions	0	0	0
Uncollectible accounts written-off	0	65	51
Balance at end of period	$ 418	$ 251	$ 256