SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Bad Debts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 605	$ 490	$ 294
Additions	344	379	354
Write-offs	(306)	(264)	(158)
Ending Balance	643	605	490
Allowance for Customer Credits [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	439	280	111
Additions	592	803	1,037
Write-offs	(660)	(644)	(868)
Ending Balance	371	439	280
Tax Valuation Allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	5,427	6,015	6,356
Charged (credit) to tax expense	(771)	(588)	(341)
Ending Balance	$ 4,656	$ 5,427	$ 6,015