Sales of Certain Receivables - Sales of Service Receivables (Details) - USD ($)	Jun. 30, 2020	Apr. 01, 2020	Dec. 31, 2019	Dec. 31, 2014
Variable Interest Entity [Line Items]
Other current assets	$ 2,586,000,000		$ 1,972,000,000
Accounts payable and accrued liabilities	9,348,000,000		6,746,000,000
Other current liabilities	1,669,000,000		1,673,000,000
Factoring Arrangement | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Revolving receivables facility, maximum borrowing capacity				$ 950,000,000
Revolving receivables facility, outstanding borrowings	914,000,000		924,000,000
Other current assets	352,000,000		350,000,000
Accounts payable and accrued liabilities	0		25,000,000
Other current liabilities	$ 360,000,000		$ 342,000,000
Sprint | Accounts receivable facility
Variable Interest Entity [Line Items]
Total amount outstanding		$ 2,300,000,000