Credit Losses on Financial Instruments (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance at January 1, 2020	$ 35
Provision for expected losses	66
Write-offs charged against the allowance	(48)
Recoveries collected	8
Ending balance at December 31, 2020	61
Business
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance at January 1, 2020	17
Provision for expected losses	30
Write-offs charged against the allowance	(22)
Recoveries collected	4
Ending balance at December 31, 2020	29
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance at January 1, 2020	18
Provision for expected losses	36
Write-offs charged against the allowance	(26)
Recoveries collected	4
Ending balance at December 31, 2020	$ 32