Property, Plant and Equipment

12 Months Ended

Dec. 31, 2021

Property, Plant and Equipment [Abstract]

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


	Depreciable Lives	As of December 31,
		2021		2020
		(Dollars in millions)
Land	N/A	$	305	320
Fiber conduit and other outside plant (1)	15-45 years	5,531		6,186
Central office and other network electronics (2)	7-10 years	3,280		3,388
Support assets (3)	3-30 years	2,504		2,722
Construction-in-progress (4)	N/A	624		720
Gross property, plant and equipment		12,244		13,336
Accumulated depreciation		(3,202)		(2,818)
Net property, plant and equipment		$	9,042	10,518

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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.

At December 31, 2021, we classified certain property, plant and equipment as held for sale and discontinued recording depreciation on the planned divestiture of our Latin American business. See Note 2—Planned Divestiture of the Latin American Business for more information.

Depreciation expense was $874 million, $851 million and $804 million for the years ended December 31, 2021, 2020 and 2019, respectively.

Asset Retirement Obligations

As of December 31, 2021 and 2020, 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,
	2021		2020	2019
	(Dollars in millions)
Balance at beginning of period	$	122	113	105
Accretion expense	5		6	5
Liabilities settled	(10)		(7)	(12)
Revision in estimated cash flows	7		10	15
Reclassified as held for sale (1)	(3)		—	—
Balance at end of period	$	121	122	113

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(1)Represents the amounts reclassified as held for sale related to our planned divestiture. See Note 2—Planned Divestiture of the Latin American Business.