Other Long-Term Assets, Net

Other long-term assets, net of accumulated amortization, consisted of the following (in millions):



	December 31,
	2018			2017
Intangible assets ⁽¹⁾	$	1,209		$	1,265
Other	144			60
	1,353			1,325
Accumulated amortization	(437		)	(421		)
	$	916		$	904


⁽¹⁾	We include rights-of-way, which are intangible assets, in our pipeline and related facilities amounts within property and equipment. See Note 6 for a discussion of property and equipment.

Amortization expense for finite-lived intangible assets for the years ended December 31, 2018, 2017 and 2016 was $66 million, $54 million and $44 million, respectively.

Intangible assets that have finite lives are tested for impairment when events or circumstances indicate that the carrying value may not be recoverable. We did not recognize any impairments of finite-lived intangible assets during the three years ended December 31, 2018. Our intangible assets that have finite lives consisted of the following (in millions):



		December 31, 2018							December 31, 2017
	Estimated Useful Lives (Years)	Cost		Accumulated Amortization			Net		Cost		Accumulated Amortization			Net
Customer contracts and relationships	1 – 20	$	1,152	$	(413	)	$	739	$	1,188	$	(383	)	$	805
Property tax abatement	7 – 13	23		(16		)	7		38		(30		)	8
Other agreements	25 – 70	34		(8		)	26		39		(8		)	31
		$	1,209	$	(437	)	$	772	$	1,265	$	(421	)	$	844

We estimate that our amortization expense related to finite-lived intangible assets for the next five years will be as follows (in millions):



2019	$	70
2020	$	75
2021	$	75
2022	$	73
2023	$	68