Loans and Related Allowance for Credit Losses, Credit Quality Indicators for Credit Card Loans (Details) - Total Consumer [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total loans	$ 379,069		$ 379,069		$ 389,255
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Loan charge-offs, loans	1,016	$ 887	3,095	$ 2,466
Credit card [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Revolving loans, finance receivable	54,452		54,452		51,805
Revolving loans converted to term loans, finance receivable	594		594		425
Total loans	55,046		55,046		52,230
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Revolving loans, charge-offs			1,986		1,909
Revolving loans converted to term loans, charge-offs			123		100
Loan charge-offs, loans	700	$ 503	2,109	$ 1,407	2,009
Credit card [Member] | FICO 740 or more [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Revolving loans, finance receivable	20,971		20,971		19,153
Revolving loans converted to term loans, finance receivable	27		27		21
Total loans	20,998		20,998		19,174
Credit card [Member] | FICO 700 to 739 [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Revolving loans, finance receivable	12,201		12,201		11,727
Revolving loans converted to term loans, finance receivable	69		69		51
Total loans	12,270		12,270		11,778
Credit card [Member] | FICO 660 to 699 [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Revolving loans, finance receivable	10,873		10,873		10,592
Revolving loans converted to term loans, finance receivable	121		121		84
Total loans	10,994		10,994		10,676
Credit card [Member] | FICO 620 to 659 [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Revolving loans, finance receivable	5,266		5,266		5,273
Revolving loans converted to term loans, finance receivable	108		108		76
Total loans	5,374		5,374		5,349
Credit card [Member] | FICO less than 620 [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Revolving loans, finance receivable	5,018		5,018		4,861
Revolving loans converted to term loans, finance receivable	267		267		192
Total loans	5,285		5,285		5,053
Credit card [Member] | No FICO available [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Revolving loans, finance receivable	123		123		199
Revolving loans converted to term loans, finance receivable	2		2		1
Total loans	125		125		200
Credit card [Member] | Current-29 days past due [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Revolving loans, finance receivable	53,002		53,002		50,428
Revolving loans converted to term loans, finance receivable	494		494		350
Total loans	53,496		53,496		50,778
Credit card [Member] | 30 to 89 days past due [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Revolving loans, finance receivable	700		700		660
Revolving loans converted to term loans, finance receivable	65		65		49
Total loans	765		765		709
Credit card [Member] | 90 days or more past due [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Revolving loans, finance receivable	750		750		717
Revolving loans converted to term loans, finance receivable	35		35		26
Total loans	$ 785		$ 785		$ 743