TriVascular Merger (Carrying Amount of Goodwill) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 28,685	[1]
Goodwill, ending balance	120,711	[1]
TriVascular Technologies, Inc.
Goodwill [Roll Forward]
Goodwill, beginning balance	28,685
Goodwill acquired from the Merger	92,086
Foreign currency translation adjustment	$ (60)

[1] Difference in the value between these dates is mainly due to acquisition of TriVascular. Refer to Note 13 of the consolidated financial statements for further discussion.