Property, Plant and Equipment

12 Months Ended

Dec. 31, 2024

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Note 9— Property, Plant and Equipment

Net property, plant and equipment is composed of the following:

	Depreciable Lives	As of December 31,
		2024		2023
		(Dollars in millions)
Land	N/A	$	191	202
Fiber conduit and other outside plant (1)	15-45 years	4,563		4,380
Central office and other network electronics (2)	7-10 years	3,752		3,467
Support assets (3)	3-30 years	2,278		2,252
Construction-in-progress (4)	N/A	909		762
Gross property, plant and equipment		11,693		11,063
Accumulated depreciation		(4,139)		(3,665)
Net property, plant and equipment		$	7,554	7,398

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(1)Fiber, conduit and other outside plant consists of fiber and metallic cable, conduit, poles and other supporting structures.

(2)Central office and other network electronics consists of circuit and packet switches, routers, transmission electronics and electronics providing service to customers.

(3)Support assets consist of buildings, data centers, computers and other administrative and support equipment.

(4)Construction in progress includes construction and property of the aforementioned categories that has not been placed in service as it is still under construction.

Depreciation expense was $676 million, $686 million and $790 million for the years ended December 31, 2024, 2023 and 2022, respectively.

During 2024, we initiated marketing our Broomfield, Colorado office buildings to locate a buyer and have classified those buildings as held for sale resulting in an impairment loss of $80 million.

Asset Retirement Obligations

As of December 31, 2024 and 2023, our asset retirement obligations consisted primarily of restoration requirements for leased facilities. We recognize our estimate of the fair value of our asset retirement obligations in the period incurred in other long-term liabilities. The fair value of the asset retirement obligation is also capitalized as property, plant and equipment and then depreciated over the estimated remaining useful life of the associated asset.

The following table provides asset retirement obligation activity:

	Years Ended December 31,
	2024		2023
	(Dollars in millions)
Balance at beginning of period	$	94	85
Accretion expense	6		4
Liabilities settled	(10)		(6)
Change in estimate	7		11
Balance at end of period	$	97	94

The change in estimate referred to in the table above was offset against gross property, plant and equipment.