Credit Losses on Financial Instruments (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021 USD ($)
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 61
Provision for expected losses	12
Write-offs charged against the allowance	(38)
Recoveries collected	9
Ending balance	44
Consumer Reclassed to Mass Market
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	32
Business Reclassed to Mass Markets
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	4
Mass Market Portfolio
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	36
Provision for expected losses	7
Write-offs charged against the allowance	(27)
Recoveries collected	8
Ending balance	24
Business Portfolio
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	25
Provision for expected losses	5
Write-offs charged against the allowance	(11)
Recoveries collected	1
Ending balance	$ 20