Loan Receivables (Schedule of Loan Receivables) (Details) - USD ($) $ in Millions		Mar. 31, 2020		Jan. 01, 2020	Dec. 31, 2019		Mar. 31, 2019	[3]	Dec. 31, 2018	[3]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables		$ 92,963			$ 95,894
Allowance for credit losses		(6,913)	[1],[2]	$ (5,844)	(3,383)	[1],[2],[3]	$ (3,134)		$ (3,041)
Net loan receivables		86,050			92,511
Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables		29,436			31,840
Allowance for credit losses	[4]	(1,620)			(1,179)
Credit Card Securitization Trusts [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[5]	29,149			31,548
Allowance for credit losses	[5],[6]	(1,620)			(1,179)
Net loan receivables		27,529			30,369
Seller's interest		10,799			12,652
Student Loan Securitization Trusts [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables		287			292
Credit Card Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[7],[8]	73,811			77,181
Allowance for credit losses		(5,306)		(4,550)	(2,883)	[3]	(2,622)		(2,528)
Accrued interest receivable		425			471
Credit Card Loans [Member] | Credit Card Securitization Trusts [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investors' interest		18,400			18,900
Seller's interest		10,800			12,700
Total Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[9]	19,152			18,713
Total Other Loans [Member] | Private Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[9],[10]	9,957			9,653
Allowance for credit losses		(765)		(653)	(148)	[3]	(168)		(169)
Accrued interest receivable		495			461
Total Other Loans [Member] | Private Student Loans [Member] | Student Loan Securitization Trusts [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans pledged as collateral		287			292
Total Other Loans [Member] | Personal Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[9]	7,651			7,687
Allowance for credit losses		(807)		(613)	(348)	[3]	(338)		(338)
Accrued interest receivable		53			53
Total Other Loans [Member] | Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan receivables	[9]	1,544			1,373
Allowance for credit losses		(35)		$ (28)	(4)	[3]	$ (6)		$ (6)
Accrued interest receivable		$ 5			$ 4

[1] Prior to adoption of Accounting Standards Update ("ASU") No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

[2] Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

[3] Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

[4] Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

[5] The Company maintains its allowance for credit losses at an amount sufficient to absorb expected losses inherent in all loan receivables, which includes all loan receivables in the trusts. Therefore, credit risk associated with the transferred receivables is fully reflected on the Company's balance sheet in accordance with GAAP.

[6] Prior to adoption of ASU No. 2016-13 on January 1, 2020, credit losses were estimated using the incurred loss approach.

[7] Amounts include carrying values of $18.4 billion and $18.9 billion underlying investors' interest in trust debt at March 31, 2020 and December 31, 2019, respectively, and $10.8 billion and $12.7 billion in seller's interest at March 31, 2020 and December 31, 2019, respectively. See Note 4: Credit Card and Student Loan Securitization Activities for additional information.

[8] Unbilled accrued interest receivable on credit card loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $425 million and $471 million at March 31, 2020 and December 31, 2019, respectively.

[9] Accrued interest receivable on private student, personal and other loans, which is presented as part of other assets in the Company's condensed consolidated statements of financial condition, was $495 million, $53 million and $5 million, respectively, at March 31, 2020 and $461 million, $53 million and $4 million, respectively, at December 31, 2019.

[10] Amounts include carrying values of $287 million and $292 million in loans pledged as collateral against the note issued from a student loan securitization trust at March 31, 2020 and December 31, 2019, respectively. See Note 4: Credit Card and Student Loan Securitization Activities for additional information.