Commitments and Contingencies (Narrative) (Details) ft² in Thousands, $ in Thousands		3 Months Ended
	Mar. 17, 2016 USD ($)	Mar. 31, 2017 USD ($) ft²	Mar. 31, 2016 USD ($)
Operating Leased Assets [Line Items]
Rent expense		$ 900	$ 800
Settlement costs from litigation	$ 4,700	0	4,650
Termination costs		$ 15,662	38,404
Contract Termination
Operating Leased Assets [Line Items]
Termination costs			$ 1,600
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
TriVascular Technologies, Inc.
Operating Leased Assets [Line Items]
Renewal term		5 years
TriVascular Technologies, Inc. | Manufacturing Facility
Operating Leased Assets [Line Items]
Aggregate square feet | ft²		110