Background (Details) - USD ($)		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Jan. 01, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Book overdraft balance		$ 0			$ 106,000,000
Revenues	[1]	(5,228,000,000)	$ (5,427,000,000)
Reduction to cost of services and products	[1]	(2,235,000,000)	(2,300,000,000)
Lease income		$ 333,000,000	$ 199,000,000
Percent of operating revenue		6.00%	4.00%
ACCUMULATED DEFICIT | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption of ASU				$ 9,000,000
Change in Accounting Principle, Universal Service Fund
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues		$ 215,000,000	$ 220,000,000
Reduction to cost of services and products		$ 215,000,000	$ 220,000,000

[1] Reclassifications were made within certain 2019 comparative figures due to the retrospective application of an accounting policy election during the first quarter of 2020. Refer to Note 1 - Background and our Form 8-K filing dated April 30, 2020 for further information.