6. Goodwill and Other Intangible Assets

Indefinite Lived Intangible Assets

As of September 30, 2018 and December 31, 2017 the carrying values of our indefinite lived intangible assets were as follows (in thousands):


	September 30,		December 31,
	2018		2017
Goodwill	$	188,118	$	188,305
In-process R&D		9,485		13,954
Procurement contracts and agreements		2,013		2,013
Trademarks		841		841

Based on our experience with similar agreements, we believe that our acquired procurement contracts and agreements have indefinite useful lives, as we expect to continue to renew these contracts for the foreseeable future. We believe that our trademarks have indefinite useful lives as we currently anticipate that our trademarks will contribute to our cash flows indefinitely.

We monitor the phases of development of all in-process R&D projects, including the risks associated with further development and the amount and timing of benefits expected to be derived from the completed projects. Incremental costs associated with development are charged to expense as incurred. Capitalized costs are amortized over the estimated useful life of the developed asset once completed. All in-process R&D projects are reviewed for impairment annually or more frequently if events or changes in circumstances indicate that the asset might be impaired.

As of September 30, 2018 and December 31, 2017 our entire goodwill balance was related to our Medical Devices segment.


	Medical Devices Segment
Balance as of December 31, 2017	$	188,305
JOTEC Acquisition measurement period adjustments		3,177
Revaluation of goodwill denominated in foreign currency		(3,364)
Balance as of September 30, 2018	$	188,118

Definite Lived Intangible Assets

As of September 30, 2018 and December 31, 2017 the gross carrying values, accumulated amortization, and approximate amortization period of our definite lived intangible assets were as follows (in thousands):


	Gross Carrying		Accumulated		Amortization
September 30, 2018	Value		Amortization		Period
Acquired technology	$	136,061	$	14,807	11	–	22	Years
Customer lists and relationships		31,191		4,702	13	–	22	Years
Distribution and manufacturing rights and know-how		4,059		2,035	11	–	15	Years
Patents		3,621		2,918			17	Years
Other		2,096		1,467	3	–	5	Years

	Gross Carrying		Accumulated		Amortization
December 31, 2017	Value		Amortization		Period
Acquired technology	$	139,045	$	8,686	11	–	22	Years
Customer lists and relationships		32,419		3,552	13	–	23	Years
Distribution and manufacturing rights and know-how		4,059		1,820	11	–	15	Years
Patents		3,612		2,819			17	Years
Other		1,439		1,075			3	Years

Amortization Expense

The following is a summary of amortization expense as recorded in general, administrative, and marketing expenses on our Summary Consolidated Statement of Operations and Comprehensive Income (Loss) (in thousands):


	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
Amortization expense	$	2,707	$	1,140	$	8,195	$	3,423

As of September 30, 2018 scheduled amortization of intangible assets for the next five years is as follows (in thousands):


	Remainder
	of 2018		2019		2020		2021		2022		2023		Total
Amortization expense	$	2,597	$	10,386	$	10,222	$	10,202	$	9,673	$	9,287	$	52,367