Revenue Recognition (Analysis of Product Return Liability) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Revenue Recognition
Beginning balance	$ 2,621	$ 2,408
Provision for product returns	637	1,179
Credits issued to third parties	(715)	(977)
Ending balance	$ 2,543	$ 2,610
Aggregate product return rate	1.10%	1.10%