Agreements With Endospan (Narrative) (Details) - Endospan [Member] - USD ($)		1 Months Ended	3 Months Ended
	Sep. 11, 2019	Sep. 30, 2019	Mar. 31, 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
Required percentage of number of patients before third tranche of loan funding can be acquired	50.00%
Investment in VIE	$ 15,000,000.0		$ 15,000,000.0
Additional amounts			0
Endospan loan, fair value		358,000
Securities option agreement, fair value			4,800,000
Distribution agreements, fair value			$ 8,500,000	$ 9,800,000
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 amount	15,000,000.0
JOTEC [Member]
Variable Interest Entity [Line Items]
Distribution fee	$ 9,000,000.0