Goodwill, Customer Relationships and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of goodwill, customer relationships and other intangible assets

Goodwill, customer relationships and other intangible assets consisted of the following:

	As of December 31,
	2019		2018
	(Dollars in millions)
Goodwill	$	9,360	9,360
Customer relationships, less accumulated amortization of $5,231 and $4,806	$	468	893
Other intangible assets subject to amortization:
Capitalized software, less accumulated amortization of $1,780 and $1,712	$	311	311

Summary of amortization expense

Total amortization expense for intangible assets was as follows:

	Years Ended December 31,
	2019		2018	2017
	(Dollars in millions)
Amortization expense for intangible assets	$	533	581	671

Schedule of estimated amortization expense for intangible assets

We estimate that total amortization expense for intangible assets for the years ending December 31, 2020 through 2024 will be as follows:

	(Dollars in millions)
Year ending December 31,
2020	$	475
2021	182
2022	87
2023	9
2024	9