Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment

The components of property and equipment were as follows:

(in millions)	Useful Lives	December 31, 2019		December 31, 2018
Buildings and equipment	Up to 40 years	$	2,587	$	2,428
Wireless communications systems	Up to 20 years	34,353		35,282
Leasehold improvements	Up to 12 years	1,345		1,299
Capitalized software	Up to 10 years	12,705		11,712
Leased wireless devices	Up to 18 months	1,139		1,159
Construction in progress		2,973		2,776
Accumulated depreciation and amortization		(33,118)		(31,297)
Property and equipment, net		$	21,984	$	23,359

Schedule of Asset Retirement Obligations

Activity in our asset retirement obligations was as follows:

(in millions)	December 31, 2019		December 31, 2018
Asset retirement obligations, beginning of year	$	609	$	562
Liabilities incurred	35		26
Liabilities settled	(2)		(9)
Accretion expense	32		30
Changes in estimated cash flows	(15)		—
Asset retirement obligations, end of year	$	659	$	609
Classified on the balance sheet as:
Other long-term liabilities	$	659	$	609