Acquisitions and Divestitures - Spectrum License Transactions (Details) $ in Millions	1 Months Ended				3 Months Ended		12 Months Ended
	Jan. 31, 2022 USD ($)	Feb. 28, 2021 USD ($) license	Sep. 30, 2020 USD ($) license	Mar. 31, 2020 USD ($) license	Mar. 31, 2021 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Business Acquisition [Line Items]
Payments for deposits							$ 47,596	$ 3,896	$ 898
Loss on disposition of licenses, pre-tax							223	1,195	$ 0
Spectrum Licenses
Business Acquisition [Line Items]
Number of licenses acquired | license				4,940
Business acquisition consideration				$ 3,400
Portion of price settled				1,800
Loss on disposition of licenses, pre-tax								1,200
Loss on disposition of licenses								914
Priority Access Licenses
Business Acquisition [Line Items]
Number of licenses acquired | license			557
Payments for deposits			$ 1,900
Spectrum Licenses
Business Acquisition [Line Items]
Payments for deposits				$ 1,600		$ 101
Spectrum Licenses | Various Other Wireless Licenses
Business Acquisition [Line Items]
Payments for deposits							95	$ 360
Loss on disposition of licenses, pre-tax							223
Loss on disposition of licenses							167
Spectrum Licenses, C-Band | Spectrum Licenses
Business Acquisition [Line Items]
Number of licenses acquired | license		3,511
Payments for deposits					$ 44,600		$ 45,500
Estimated clearing and incentive costs		$ 7,700
Average remaining renewal period of wireless license portfolio (in years)							15 years
Spectrum Licenses, C-Band | Spectrum Licenses | Projected Clearing Costs
Business Acquisition [Line Items]
Payments for deposits							$ 1,300
Spectrum Licenses, C-Band | Spectrum Licenses | Subsequent event | Projected Clearing Costs
Business Acquisition [Line Items]
Payments for deposits	$ 1,400