Intangible Assets

12 Months Ended

Dec. 31, 2018

Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]

Intangible assets as of December 31, 2018 consist of the following (in millions):



	Cost		Accumulated Amortization			Net
Customer relationships and other	$	6,011	$	(2,944	)	$	3,067
Finite-lived trademarks	68		(46		)	22
Indefinite-lived trademarks	43		—			43
Total intangible assets, net	$	6,122	$	(2,990	)	$	3,132

Intangible assets as of December 31, 2017 consist of the following (in millions):



	Cost		Accumulated Amortization			Net
Customer relationships and other	$	6,220	$	(2,427	)	$	3,793
Finite-lived trademarks	101		(57		)	44
Indefinite-lived trademarks	48		—			48
Total intangible assets, net	$	6,369	$	(2,484	)	$	3,885

Amortization expense for intangible assets with finite lives, including the contract intangible in our Brazilian Venture, which was amortized as a reduction of revenue until impaired (see Note 16), was $659 million, $670 million and $518 million for the years ended December 31, 2018, 2017 and 2016, respectively.

Estimated amortization of intangible assets for the next five years is as follows (in millions):



2019	$	626
2020	458
2021	443
2022	426
2023	405