Goodwill, Customer Relationships and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2016

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,
	2016		2015
	(Dollars in millions)
Goodwill	$	9,354	9,354
Customer relationships, less accumulated amortization of $3,822 and $3,264	$	1,877	2,435
Other intangible assets subject to amortization:
Capitalized software, less accumulated amortization of $1,510 and $1,383	$	471	613

Summary of amortization expense

Total amortization expense for intangible assets was as follows:

	Years Ended December 31,
	2016		2015	2014
	(Dollars in millions)
Amortization expense for intangible assets	$	767	871	957

Schedule of estimated amortization expense for intangible assets

We estimate that total amortization expense for intangible assets for the years ending December 31, 2017 through 2021 will be as follows:

	(Dollars in millions)
Year ending December 31,
2017	$	652
2018	584
2019	509
2020	440
2021	127