Property, Plant and Equipment

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, Plant and Equipment

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

	Depreciable Lives	As of December 31,
		2019		2018
		(Dollars in millions)
Land	N/A	336		339
Fiber conduit and other outside plant(1)	15-45 years	5,226		5,262
Central office and other network electronics(2)	7-10 years	2,687		1,986
Support assets(3)	3-30 years	2,419		2,327
Construction-in-progress(4)	N/A	1,093		560
Gross property, plant and equipment		11,761		10,474
Accumulated depreciation(5)		(1,825	)	(1,021	)
Net property, plant and equipment		9,936		9,453

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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.
(5)	CenturyLink's acquisition of us caused our assets and liabilities to be recognized at fair value and resulted in accumulated depreciation being reset as of the date of acquisition.

Depreciation expense was $804 million and $906 million for the years ended December 31, 2019 and December 31, 2018, respectively, $143 million for the successor period ended December 31, 2017 and $850 million for the predecessor period ended October 31, 2017.

Asset Retirement Obligations

At December 31, 2019 and 2018, 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:

	Successor							Predecessor
	Year Ended December 31, 2019			Year Ended December 31, 2018		Period Ended December 31, 2017		Period Ended October 31, 2017
	(Dollars in millions)
Balance at beginning of period	$	105		45		45		89
Accretion expense	5			5		1		12
Purchase price adjustments (1)	—			58		—		—
Liabilities settled	(12		)	(13	)	(1	)	(7	)
Revision in estimated cash flows	15			10		—		—
Balance at end of period	$	113		105		45		94

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(1) These liabilities relate to purchase price adjustments that occurred during 2018 from CenturyLink's acquisition of us.