Intangible Assets

12 Months Ended

Sep. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

10.INTANGIBLE ASSETS

The table below provides details of acquired intangible assets:

	September 30, 2018							September 30, 2017
	Gross		Accumulated Amortization			Net		Gross		Accumulated Amortization			Net
(In millions)
Customer relationships	$	79.5	$	(26.5	)	$	53.0	$	79.5	$	(22.7	)	$	56.8
Patents and technology	50.3		(41.3		)	9.0		50.3		(37.9		)	12.4
Other	3.2		(1.7		)	1.5		3.2		(1.6		)	1.6
Total Intangible Assets	$	133.0	$	(69.5	)	$	63.5	$	133.0	$	(62.2	)	$	70.8

The intangible assets primarily pertain to the Materials segment and have a remaining useful life of approximately 16 years for customer relationships and 4 years for patents and technology.

Amortization expense for intangible assets was $7.2 million, $7.6 million, and $7.5 million in 2018, 2017, and 2016, respectively.

Projected annual amortization expense for intangible assets as of September 30, 2018 is as follows:

2019	$	5.9
2020	5.8
2021	5.8
2022	4.9
2023	3.8
Thereafter	37.3
Total	$	63.5

In 2017, Versum acquired the intellectual property and related assets of Dynaloy through a business combination. Refer to Note 23, "Acquisition," for further discussion of the related intangible assets and goodwill.