Schedule II. - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation and Qualifying Accounts
Balance at beginning of year	$ 451	$ 317	$ 371
Charged to cost and expenses	74	240	51
Deduction	(150)	(106)	(105)
Balance at end of year	$ 375	$ 451	$ 317