SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - Allowance for doubtful accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deduction from asset accounts:
Balance at Beginning of Period	$ 1,038	$ 1,004	$ 1,864
Charged to Expense	214	86	(462)
Accounts Written Off	(140)	(52)	(398)
Balance at End of Period	$ 1,112	$ 1,038	$ 1,004