Agreements With Endospan (Narrative) (Details) - Endospan [Member] - USD ($)			1 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 11, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Securities purchase option agreement		$ 1,000,000.0		$ 1,000,000.0
Securities purchase option agreement, expiration period					90 days
Per three tranches of funding		$ 5,000,000.0
Funded second tranche payment			$ 5,000,000.0
Required percentage of number of patients before third tranche of loan funding can be acquired		50.00%
Investment in VIE	$ 20,000,000.0	$ 15,000,000.0
Additional amounts			5,000,000.0
Endospan loan, fair value	409,000		409,000		$ 409,000	$ 358,000
Securities option agreement, fair value	4,800,000		4,800,000		4,800,000
Distribution agreements, fair value	$ 8,100,000		$ 8,100,000		8,100,000	$ 9,800,000
Expense from fair value adjustment					$ 4,900,000
Minimum [Member]
Variable Interest Entity [Line Items]
Option to purchase outstanding securities				350,000,000.0
Maximum [Member]
Variable Interest Entity [Line Items]
Option to purchase outstanding securities				$ 450,000,000.0
Secured Debt [Member]
Variable Interest Entity [Line Items]
Loan provided		15,000,000.0
JOTEC GmbH [Member]
Variable Interest Entity [Line Items]
Distribution fee		$ 9,000,000.0