Goodwill, Customer Relationships and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2015

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,
	2015		2014
	(Dollars in millions)
Goodwill	$	9,354	9,354
Customer relationships, less accumulated amortization of $3,264 and $2,660	2,435		3,039
Other intangible assets subject to amortization:
Capitalized software, less accumulated amortization of $1,383 and $1,247	613		808

Summary of amortization expense

Total amortization expense for intangible assets was as follows:

	Years Ended December 31,
	2015		2014	2013
	(Dollars in millions)
Amortization expense for intangible assets	$	871	957	1,029

Schedule of estimated amortization expense for intangible assets

We estimate that total amortization expense for intangible assets for the years ending December 31, 2016 through 2020 will be as follows:

	(Dollars in millions)
Year ending December 31,
2016	$	725
2017	661
2018	587
2019	507
2020	435