Card Member Receivables and Card Member Loans (Details) - USD ($) $ in Millions	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Card Member Receivables
Financing Receivable Segment [Abstract]
Financing receivables, gross	$ 12,868		$ 12,157
Less: Reserves for credit losses	(4)	$ 30	70	$ 184	$ 69	$ 15
Financing receivables, net	12,872		12,087
Deferred discount revenue on card member receivable	20		19
Card Member Loans
Financing Receivable Segment [Abstract]
Less: Reserves for credit losses	21	$ 24	20	$ 23	$ 18	$ 17
Financing receivables, net	458		480
Global Consumer Services Group | Card Member Receivables
Financing Receivable Segment [Abstract]
Financing receivables, gross	2,169		2,157
Global Consumer Services Group | Card Member Loans
Financing Receivable Segment [Abstract]
Financing receivables, gross	479		500
Less: Reserves for credit losses	21		20
Financing receivables, net	458		480
Global Commercial Services | Card Member Receivables
Financing Receivable Segment [Abstract]
Financing receivables, gross	$ 10,699		$ 10,000