8. Intangible Assets

Intangible assets consist principally of acquired patents and technology, customer lists and relationships, licenses and trademarks. The Company recorded amortization expense of $0.7 million and $0.6 million for the three months ended March 31, 2018 and 2017, respectively. The Company recorded amortization expense of $1.4 million and $1.3 million for the six months ended March 31, 2018 and 2017, respectively.

Intangible assets consisted of the following:

	March 31, 2018
(Dollars in thousands)	Weighted Average Original Life (Years)		Gross Carrying Amount		Accumulated Amortization			Net
Definite-lived intangible assets:
Customer lists and relationships		8.9	$	18,832	$	(8,777	)	$	10,055
Developed technology		11.5		9,829		(1,950	)		7,879
Non-compete		5.0		230		(127	)		103
Patents and other		16.5		2,321		(1,496	)		825
Subtotal				31,212		(12,350	)		18,862
Unamortized intangible assets:
In-process research and development				283		—			283
Trademarks and trade names				580		—			580
Total			$	32,075	$	(12,350	)	$	19,725

	September 30, 2017
(Dollars in thousands)	Weighted Average Original Life (Years)		Gross Carrying Amount		Accumulated Amortization			Net
Definite-lived intangible assets:
Customer lists and relationships		8.9	$	18,293	$	(7,834	)	$	10,459
Developed technology		11.7		9,297		(1,478	)		7,819
Non-compete		5.0		230		(103	)		127
Patents and other		16.5		2,321		(1,423	)		898
Subtotal				30,141		(10,838	)		19,303
Unamortized intangible assets:
In-process research and development				679		—			679
Trademarks and trade names				580		—			580
Total			$	31,400	$	(10,838	)	$	20,562

Based on the intangible assets in service as of March 31, 2018, excluding any possible future amortization associated with acquired in-process research and development (“IPR&D”), which has not met technological feasibility as of March 31, 2018, estimated amortization expense for the remainder of fiscal 2018 and each of the next five fiscal years is as follows (in thousands):

Remainder of 2018	$	1,398
2019		2,795
2020		2,620
2021		2,481
2022		2,441
2023		1,807

Future amortization amounts presented above are estimates. Actual future amortization expense may be different as a result of future acquisitions, impairments, completion or abandonment of IPR&D intangible assets, changes in amortization periods, or other factors.

The Company defines IPR&D as the value of technology acquired for which the related projects have substance and are incomplete. IPR&D acquired in a business acquisition is recognized at fair value and requires the IPR&D to be capitalized as an indefinite-lived intangible asset until completion of the IPR&D project or abandonment. Upon completion of the development project (generally when regulatory approval to market the product is obtained), an impairment assessment is performed prior to amortizing the asset over its estimated useful life. If the IPR&D projects are abandoned, the related IPR&D assets would be written off. During the second quarter of fiscal 2018, we reclassified $0.4 million of acquired IPR&D to developed technology as the technology was commercialized.