DEFINITE-LIVED LONG-LIVED ASSETS

The Company’s definite-lived long-lived assets include property, plant, and equipment as well as other intangible assets with definite lives. Refer to Note 16, Supplemental Balance Sheet Information for details related to property, plant and equipment.

The details of other intangible assets subject to amortization as of June 30, 2018 and June 30, 2017, are as follows:



(Dollars in millions)	Weighted Average Life	Gross Carrying Value		Accumulated Amortization			Net Carrying Value
June 30, 2018
Amortized intangibles:
Core technology	18 years	$	170.8	$	(85.3	)	$	85.5
Customer relationships	14 years	587.0		(140.9		)	446.1
Product relationships	12 years	210.5		(197.2		)	13.3
Total intangible assets		$	968.3	$	(423.4	)	$	544.9



(Dollars in millions)	Weighted Average Life	Gross Carrying Value		Accumulated Amortization			Net Carrying Value
June 30, 2017
Amortized intangibles:
Core technology	18 years	$	170.3	$	(74.8	)	$	95.5
Customer relationships	14 years	253.0		(106.1		)	146.9
Product relationships	12 years	206.9		(176.2		)	30.7
Total intangible assets		$	630.2	$	(357.1	)	$	273.1

Amortization expense was $62.6 million, $44.3 million, and $46.4 million for the fiscal year ended June 30, 2018, June 30, 2017, and June 30, 2016, respectively. Future amortization expense for the next five years is estimated to be:



(Dollars in millions)	2019		2020		2021		2022		2023
Amortization expense	$	63.5	$	49.5	$	49.5	$	49.5	$	49.5

The Company impaired definite-lived intangible assets of $0.6 million, $3.4 million, and $0.7 million in the fiscal years ended June 30, 2018, 2017, and 2016, respectively.