v3.24.4
Long-Term Borrowings (Schedule of Long-Term Borrowings and Weighted Average Interest Rates) (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Dec. 31, 2023
Dec. 31, 2023
Dec. 31, 2022
Debt Instrument [Line Items]      
Long-term borrowings $ 20,581 $ 20,581 $ 20,108
Parent Company [Member]      
Debt Instrument [Line Items]      
Long-term borrowings 4,469 4,469 3,487
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member]      
Debt Instrument [Line Items]      
Long-term borrowings $ 10,928 $ 10,928 10,175
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Fixed-Rate Asset-Backed Securities [Member]      
Debt Instrument [Line Items]      
Weighted-average interest rate [1] 3.17% 3.17%  
Long-term borrowings [1] $ 10,003 $ 10,003 8,401
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Fixed-Rate Asset-Backed Securities [Member] | Minimum [Member]      
Debt Instrument [Line Items]      
Interest rate [1] 0.58% 0.58%  
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Fixed-Rate Asset-Backed Securities [Member] | Maximum [Member]      
Debt Instrument [Line Items]      
Interest rate [1] 5.03% 5.03%  
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Floating-Rate Asset-Backed Securities [Member]      
Debt Instrument [Line Items]      
Weighted-average interest rate [2] 6.08% 6.08%  
Long-term borrowings [2] $ 925 $ 925 1,774
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | 1-Month SOFR [Member]      
Debt Instrument [Line Items]      
Interest rate terms   1-month Term SOFR + 0.11448% Tenor Spread Adjustment + 60 basis points  
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | Minimum [Member]      
Debt Instrument [Line Items]      
Interest rate [2] 6.08% 6.08%  
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | Minimum [Member] | 1-Month SOFR [Member]      
Debt Instrument [Line Items]      
Basis spread on variable rate   0.60%  
Securitized Debt [Member] | Discover Card Master Trust I and Discover Card Execution Note Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | Maximum [Member]      
Debt Instrument [Line Items]      
Interest rate 6.08% 6.08%  
Securitized Debt [Member] | Student Loan Trust [Member]      
Debt Instrument [Line Items]      
Long-term borrowings $ 65 $ 65 84
Securitized Debt [Member] | Student Loan Trust [Member] | Floating-Rate Asset-Backed Securities [Member]      
Debt Instrument [Line Items]      
Weighted-average interest rate [3],[4] 9.50% 9.50%  
Long-term borrowings [3],[4] $ 65 $ 65 84
Securitized Debt [Member] | Student Loan Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | Prime Rate [Member]      
Debt Instrument [Line Items]      
Interest rate terms   Prime rate + 100 basis points  
Basis spread on variable rate   1.00%  
Securitized Debt [Member] | Student Loan Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | Minimum [Member]      
Debt Instrument [Line Items]      
Interest rate [4] 9.50% 9.50%  
Securitized Debt [Member] | Student Loan Trust [Member] | Floating-Rate Asset-Backed Securities [Member] | Maximum [Member]      
Debt Instrument [Line Items]      
Interest rate 9.50% 9.50%  
Securitized Debt [Member] | Variable Interest Entity, Primary Beneficiary [Member]      
Debt Instrument [Line Items]      
Long-term borrowings $ 10,993 $ 10,993 10,259
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed-Rate Senior Notes [Member]      
Debt Instrument [Line Items]      
Weighted-average interest rate 4.68% 4.68%  
Long-term borrowings $ 3,336 $ 3,336 3,333
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed-Rate Senior Notes [Member] | Minimum [Member]      
Debt Instrument [Line Items]      
Interest rate 3.75% 3.75%  
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed-Rate Senior Notes [Member] | Maximum [Member]      
Debt Instrument [Line Items]      
Interest rate 6.70% 6.70%  
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed Rate Retail Notes [Member]      
Debt Instrument [Line Items]      
Weighted-average interest rate 3.82% 3.82%  
Long-term borrowings $ 140 $ 140 154
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed Rate Retail Notes [Member] | Minimum [Member]      
Debt Instrument [Line Items]      
Interest rate 3.25% 3.25%  
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed Rate Retail Notes [Member] | Maximum [Member]      
Debt Instrument [Line Items]      
Interest rate 4.40% 4.40%  
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed to Floating-Rate Senior Notes      
Debt Instrument [Line Items]      
Weighted-average interest rate [5] 7.96% 7.96%  
Long-term borrowings [5] $ 993 $ 993 0
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed to Floating-Rate Senior Notes | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate      
Debt Instrument [Line Items]      
Interest rate terms SOFR + 3.370%    
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed to Floating-Rate Senior Notes | Minimum [Member]      
Debt Instrument [Line Items]      
Interest rate 7.96% 7.96%  
Corporate Debt Securities [Member] | Parent Company [Member] | Fixed to Floating-Rate Senior Notes | Maximum [Member]      
Debt Instrument [Line Items]      
Interest rate 7.96% 7.96%  
Senior Notes [Member] | Discover Bank [Member] | Fixed-Rate Senior Bank Notes [Member]      
Debt Instrument [Line Items]      
Weighted-average interest rate [1] 3.53% 3.53%  
Long-term borrowings [1] $ 3,571 $ 3,571 5,348
Senior Notes [Member] | Discover Bank [Member] | Fixed-Rate Senior Bank Notes [Member] | Minimum [Member]      
Debt Instrument [Line Items]      
Interest rate [1] 2.45% 2.45%  
Senior Notes [Member] | Discover Bank [Member] | Fixed-Rate Senior Bank Notes [Member] | Maximum [Member]      
Debt Instrument [Line Items]      
Interest rate [1] 4.65% 4.65%  
Subordinated Debt [Member] | Discover Bank [Member] | Fixed-Rate Subordinated Bank Notes [Member]      
Debt Instrument [Line Items]      
Weighted-average interest rate [1] 5.97% 5.97%  
Long-term borrowings [1] $ 500 $ 500 489
Subordinated Debt [Member] | Discover Bank [Member] | Fixed-Rate Subordinated Bank Notes [Member] | Minimum [Member]      
Debt Instrument [Line Items]      
Interest rate [1] 5.97% 5.97%  
Subordinated Debt [Member] | Discover Bank [Member] | Fixed-Rate Subordinated Bank Notes [Member] | Maximum [Member]      
Debt Instrument [Line Items]      
Interest rate [1] 5.97% 5.97%  
Federal Home Loan Bank Advances | Discover Bank [Member] | Minimum [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate      
Debt Instrument [Line Items]      
Basis spread on variable rate 0.16%    
Federal Home Loan Bank Advances | Discover Bank [Member] | Maximum [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate      
Debt Instrument [Line Items]      
Basis spread on variable rate 0.26%    
Federal Home Loan Bank Advances | Discover Bank [Member] | FixedRateFHLBAdvance      
Debt Instrument [Line Items]      
Weighted-average interest rate 4.82% 4.82%  
Long-term borrowings $ 523 $ 523 0
Federal Home Loan Bank Advances | Discover Bank [Member] | FixedRateFHLBAdvance | Minimum [Member]      
Debt Instrument [Line Items]      
Interest rate 4.77% 4.77%  
Federal Home Loan Bank Advances | Discover Bank [Member] | FixedRateFHLBAdvance | Maximum [Member]      
Debt Instrument [Line Items]      
Interest rate 4.82% 4.82%  
Federal Home Loan Bank Advances | Discover Bank [Member] | Floating Rate FHLB Advance      
Debt Instrument [Line Items]      
Weighted-average interest rate [6] 5.65% 5.65%  
Long-term borrowings [6] $ 525 $ 525 $ 525
Federal Home Loan Bank Advances | Discover Bank [Member] | Floating Rate FHLB Advance | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate      
Debt Instrument [Line Items]      
Interest rate terms SOFR plus a spread ranging from 16 to 26 basis points    
Federal Home Loan Bank Advances | Discover Bank [Member] | Floating Rate FHLB Advance | Minimum [Member]      
Debt Instrument [Line Items]      
Interest rate 5.55% 5.55%  
Federal Home Loan Bank Advances | Discover Bank [Member] | Floating Rate FHLB Advance | Maximum [Member]      
Debt Instrument [Line Items]      
Interest rate 5.65% 5.65%  
[1] The Company uses interest rate swaps to hedge portions of these long-term borrowings against changes in fair value attributable to changes in the applicable benchmark interest rates. The use of these interest rate swaps impacts the carrying value of the debt. See Note 21: Derivatives and Hedging Activities.
[2] DCENT floating-rate asset-backed securities include issuances with the following interest rate terms: 1-month Term SOFR + 0.11448% Tenor Spread Adjustment + 60 basis points as of December 31, 2023.
[3] Repayment of this debt is dependent upon the timing of principal and interest payments on the underlying private student loans. The date shown represents the final maturity date.
[4] The private student loan securitization trust floating-rate asset-backed security includes an issuance with the following interest rate term: Prime rate + 100 basis points as of December 31, 2023.
[5] The fixed to floating-rate senior notes include a rate reset on November 2, 2033, to a floating rate based on compounded SOFR + 3.370%.
[6] The floating-rate FHLB advances include interest rate terms based on SOFR plus a spread ranging from 16 to 26 basis points as of December 31, 2023