

	December 31, 2019
	Gross Amount		Accumulated Amortization			Net Amount
Core and developed technology	$	7,345.0	$	(1,733.8	)	$	5,611.2
Customer-related	916.7		(651.7		)	265.0
In-process research and development	8.8		—			8.8
Distribution rights and other	90.6		(36.1		)	54.5
Total	$	8,361.1	$	(2,421.6	)	$	5,939.5



	March 31, 2019
	Gross Amount		Accumulated Amortization			Net Amount
Core and developed technology	$	7,339.2	$	(1,102.2	)	$	6,237.0
Customer-related	917.1		(544.0		)	373.1
In-process research and development	7.7		—			7.7
Distribution rights and other	81.4		(13.6		)	67.8
Total	$	8,345.4	$	(1,659.8	)	$	6,685.6

The following is an expected amortization schedule for the intangible assets for remainder of fiscal 2020 through fiscal 2024, absent any future acquisitions or impairment charges (in millions):



Fiscal Year Ending March 31,	Projected Amortization Expense
2020	$	259.0
2021	$	972.9
2022	$	902.2
2023	$	708.4
2024	$	616.3

The Company amortizes intangible assets over their expected useful lives, which range between 1 and 15 years. Amortization expense attributed to intangible assets are assigned to cost of sales and operating expenses as follows (in millions):



	Three Months Ended December 31,				Nine Months Ended December 31,
	2019		2018		2019		2018
Amortization expense charged to cost of sales	$	2.5	$	1.8	$	7.1	$	4.9
Amortization expense charged to operating expense	256.1		195.1		770.5		500.6
Total amortization expense	$	258.6	$	196.9	$	777.6	$	505.5

The Company recognized impairment charges of $0.5 million in the nine months ended December 31, 2019, compared to $3.1 million in the nine months ended December 31, 2018. The impairment charges in the nine months ended December 31, 2018 were recognized as a result of writing off intangible assets purchased from Microsemi prior to the close of the acquisition

and as a result of changes in the combined product roadmaps after the acquisition that affected the use and life of these assets. There were no impairment charges in the three months ended December 31, 2019 and December 31, 2018.

Goodwill activity for the nine months ended December 31, 2019 was as follows (amounts in millions):



	Semiconductor Products Reporting Unit		Technology Licensing Reporting Unit
Balance at March 31, 2019	$	6,644.7	$	19.2
Additions	0.9		—
Balance at December 31, 2019	$	6,645.6	$	19.2

At March 31, 2019, the Company applied a qualitative goodwill impairment test to its two reporting units, concluding it was not more likely than not that goodwill was impaired. Through December 31, 2019, the Company has never recorded an impairment charge against its goodwill balance.