Supplemental Disclosure Of Cash Flows (Supplemental Disclosures Of Cash Flow Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Disclosure Of Cash Flows [Abstract]
Interest received	$ 1,069	$ 381	$ 1
Interest paid	72	680	716
Income taxes received	73
Income taxes paid	148	190	166
Self-fitting software acquired through liabilities incurred and exchange of investment in partnership	$ 3,093
Technology access liability		$ (375)	$ 2,600