Loans and Card Member Receivables - Modifications (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Financing Receivable, Troubled Debt Restructuring [Line Items]
Maximum payment term extension			60 months
Unused credit available	$ 50	$ 29	$ 50	$ 29
Account Balances	971	826	1,944	1,513
Card Member Loans | Interest Rate Reduction | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	$ 513	$ 348	$ 1,039	$ 642
% of Total Class of Financing Receivables	0.50%	0.40%	1.00%	0.70%
Weighted Average Interest Rate Reduction (% points)	18.20%	15.90%	18.10%	15.70%
Card Member Loans | Interest Rate Reduction | Small Business
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	$ 185	$ 149	$ 370	$ 277
% of Total Class of Financing Receivables	0.60%	0.60%	1.20%	1.10%
Weighted Average Interest Rate Reduction (% points)	17.50%	15.50%	17.50%	15.40%
Card Member Loans | Interest Rate Reduction | Corporate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	$ 0	$ 0	$ 0	$ 0
% of Total Class of Financing Receivables	0.00%	0.00%	0.00%	0.00%
Weighted Average Interest Rate Reduction (% points)	0.00%	0.00%	0.00%	0.00%
Card Member Receivables | Term Extension | Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	$ 92	$ 108	$ 184	$ 200
% of Total Class of Financing Receivables	0.40%	0.50%	0.80%	0.90%
Weighted Average Payment Term Extensions (# of months)	30 months	27 months	29 months	25 months
Card Member Receivables | Term Extension | Small Business
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	$ 142	$ 194	$ 283	$ 352
% of Total Class of Financing Receivables	0.70%	1.00%	1.50%	1.80%
Weighted Average Payment Term Extensions (# of months)	29 months	28 months	29 months	26 months
Card Member Receivables | Term Extension | Corporate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	$ 9	$ 10	$ 12	$ 15
% of Total Class of Financing Receivables	0.10%	0.10%	0.10%	0.10%
Weighted Average Payment Term Extensions (# of months)	9 months	10 months	9 months	10 months
Other Loans | Interest Rate Reduction and Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	$ 18	$ 8	$ 34	$ 13
% of Total Class of Financing Receivables	0.20%	0.10%	0.40%	0.20%
Weighted Average Interest Rate Reduction (% points)	2.50%	2.00%	2.40%	2.00%
Weighted Average Payment Term Extensions (# of months)	19 months	19 months	19 months	19 months
Other Loans | Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Account Balances	$ 12	$ 9	$ 22	$ 14
% of Total Class of Financing Receivables	0.10%	0.10%	0.30%	0.20%
Weighted Average Interest Rate Reduction (% points)	0.00%	0.00%	0.00%	0.00%
Weighted Average Payment Term Extensions (# of months)	18 months	17 months	19 months	17 months