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Goodwill, Spectrum License Transactions and Other Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Goodwill [Roll Forward]
Historical goodwill, net of accumulated impairment losses of $10,766				$ 1,901
Beginning balance		$ 1,930
Accumulated impairment losses	$ (10,984)	(10,984)		$ (10,766)
Layer3 goodwill impairment	(218)	(218)
Ending balance	$ 10,910	10,910
Layer3 TV
Goodwill [Roll Forward]
Goodwill from acquisition			$ 29
Sprint
Goodwill [Roll Forward]
Goodwill from acquisition		$ 9,198