Revenue Recognition (Analysis of Product Return Liability) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Revenue Recognition
Beginning balance	$ 2,621	$ 2,408
Provision for product returns	958	1,971
Credits issued to third parties	(873)	(1,233)
Ending balance	$ 2,706	$ 3,146
Aggregate product return rate	1.10%	1.10%