Summary of Significant Accounting Policies (Schedule Of Stock-Based Compensation Expense By Statement Of Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based employee compensation expense	$ 1,288	$ 1,223	$ 1,007
Cost of product revenue
Share-based employee compensation expense	39	37	19
Research and development expense
Share-based employee compensation expense	546	350	282
Sales, marketing, general and administrative expense
Share-based employee compensation expense	$ 703	$ 836	$ 706