Discontinued Operations - Narrative (Details) - USD ($) $ in Millions		12 Months Ended
	Jul. 01, 2020	Dec. 31, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash provided by operating activities from the Prepaid Business		$ 611
Prepaid Business \| T-Mobile and Sprint \| DISH
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments for asset acquisition	$ 1,400
Prepaid Business \| T-Mobile and Sprint \| DISH \| Transition Services Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transition period (up to)	3 years
Prepaid Business \| T-Mobile and Sprint \| DISH \| Master Network Services Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transition period (up to)	7 years
Prepaid Business \| T-Mobile and Sprint \| DISH \| EIP Receivables
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments for asset acquisition	$ 162
Prepaid Business \| DISH \| EIP Receivables
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Participation interest	100.00%
Prepaid Business, Divested Net Assets \| T-Mobile and Sprint \| DISH
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments for asset acquisition	$ 1,200
Spectrum Licenses \| T-Mobile and Sprint \| DISH
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments for asset acquisition	$ 3,600
Additional lease period	2 years
Fee liability for failure to deliver the purchase price	$ 72
Decommissioned Towers and Retail Locations \| DISH \| T-Mobile and Sprint
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Option period (up to)	5 years