Revenue from Contracts with Customers - Remaining Performance Obligations, Branded Postpaid Contracts (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 1,200
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	707
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 685
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining contract duration (in years)	1 year
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining contract duration (in years)	8 years
Postpaid service revenues
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 898
Remaining contract duration (in years)	24 months
Service performance obligations \| Sprint
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 95
Lease performance obligation \| Sprint
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 58
Remaining contract duration (in years)	18 months