Financial Statement Schedule (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowances for Doubtful Accounts
Movement in Valuation Allowances and Reserves
Balance at Beginning of Period	$ 82	$ 65	$ 64
Charged/Credited to Net Income	133	108	85
Charged to Other Account	0	0	0
Charges Utilized/Write-offs	(118)	(91)	(84)
Balance at End of Period	97	82	65
Allowance for Authorized Credits
Movement in Valuation Allowances and Reserves
Balance at Beginning of Period	28	31	29
Charged/Credited to Net Income	11	(3)	2
Charged to Other Account	0	0	0
Charges Utilized/Write-offs	0	0	0
Balance at End of Period	39	28	31
Allowance for Transaction Losses
Movement in Valuation Allowances and Reserves
Balance at Beginning of Period	23	24	21
Charged/Credited to Net Income	198	154	162
Charged to Other Account	0	0	0
Charges Utilized/Write-offs	(188)	(155)	(159)
Balance at End of Period	33	23	24
Tax Valuation Allowance
Movement in Valuation Allowances and Reserves
Balance at Beginning of Period	96	62	15
Charged/Credited to Net Income	53	42	34
Charged to Other Account	0	(1)	13
Charges Utilized/Write-offs	0	(7)	0
Balance at End of Period	$ 149	$ 96	$ 62