Schedule II - Valuation and Qualifying Accounts (Details) - Accounts receivable allowance [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 256	$ 148	$ 179
Charged/(Credited) to Costs and Expenses, Additions and Deductions	60	159	(21)
Charged to Other Accounts, Additions and Deductions	0	0	0
Uncollectible Accounts Written-off	65	51	10
Balance at End of Period	$ 251	$ 256	$ 148