Commitments and Contingencies (Narrative) (Details) ft² in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) ft²	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) ft²	Sep. 30, 2015 USD ($)
Operating Leased Assets [Line Items]
Rent expense	$ 900,000	$ 600,000	$ 2,500,000	$ 1,800,000
Settlement costs from litigation	0	0	4,650,000	0
Termination (cost) income	(11,234,000)	$ (9,334,000)	(72,865,000)	$ (31,147,000)
Contract Termination
Operating Leased Assets [Line Items]
Termination (cost) income	$ 0		$ 2,600,000
TriVascular Technologies, Inc.
Operating Leased Assets [Line Items]
Renewal term			5 years
Minimum
Operating Leased Assets [Line Items]
Severance payment, prior to change in control			6 months
Severance payment, period following change in control			18 months
Maximum
Operating Leased Assets [Line Items]
Severance payment, prior to change in control			18 months
Severance payment, period following change in control			24 months
Manufacturing Facility | TriVascular Technologies, Inc.
Operating Leased Assets [Line Items]
Aggregate square feet | ft²	110		110