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Intangible Asset, Net
 12 Months Ended
Dec. 31, 2024
Goodwill and Intangible Assets Disclosure [Abstract]  
Intangible Asset, Net Intangible Assets, Net
Intangible assets, net of accumulated amortization, consisted of the following (in millions):

December 31, 2024December 31, 2023
Estimated Useful
Lives (Years)		CostAccumulated
Amortization		NetCostAccumulated
Amortization		Net
Customer contracts and relationships
1 – 29
$2,767 $(1,105)$1,662 $2,789 $(932)$1,857 
Other agreements
15 – 70
28 (13)15 30 (12)18 
Intangible assets (1)
$2,795 $(1,118)$1,677 $2,819 $(944)$1,875 
(1)We include rights-of-way, which are intangible assets, within property and equipment. See Note 6 for a discussion of property and equipment.

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, 2024.

The majority of our finite-lived intangible assets are amortized under the declining balance method. Amortization expense for finite-lived intangible assets for the years ended December 31, 2024, 2023 and 2022 was $266 million, $308 million and $254 million, respectively. We estimate that our amortization expense related to finite-lived intangible assets for the next five years will be as follows (in millions):

2025$255 
2026$218 
2027$194 
2028$172 
2029$154