Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Goodwill, Spectrum License Transactions and Other Intangible Assets - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Apr. 01, 2020
Goodwill [Line Items]
Goodwill impairment	$ 218,000,000
Goodwill	11,117,000,000	$ 1,930,000,000
Layer3 TV
Goodwill [Line Items]
Goodwill impairment	218,000,000	$ 0	$ 0
Goodwill	$ 0
Sprint
Goodwill [Line Items]
Goodwill				$ 9,401,000,000