SCHEDULE II - VALUATION ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts receivable, allowance for doubtful accounts
Valuation accounts
Balance at Beginning of Period	$ 787	$ 912	$ 215
Additions Charged (Credited) to Expense	162	(125)	697
Balance at End of Period	949	787	912
Deferred tax valuation allowance
Valuation accounts
Balance at Beginning of Period	1,280	1,280	898
Additions Charged (Credited) to Expense	(474)		382
Balance at End of Period	$ 806	$ 1,280	$ 1,280