Revenue Recognition (Disaggregation Of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Total Sources of Revenue	$ 68,496	$ 47,818	$ 130,444	$ 92,877
Domestic Hospitals [Member]
Disaggregation of Revenue [Line Items]
Total Sources of Revenue	35,139	32,659	68,682	64,608
International Hospitals [Member]
Disaggregation of Revenue [Line Items]
Total Sources of Revenue	21,902	4,032	40,951	9,232
CardioGenesis [Member]
Disaggregation of Revenue [Line Items]
Total Sources of Revenue	1,578	2,052	2,924	3,638
International Distributor [Member]
Disaggregation of Revenue [Line Items]
Total Sources of Revenue	$ 9,877	$ 9,075	$ 17,887	$ 15,399