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Business Combinations and Discontinued Operations - Additional Information (Details) - USD ($) $ in Millions |  | 3 Months Ended | 6 Months Ended | 18 Months Ended |
--- | --- | --- | --- | --- | ---
May 18, 2025 | Jun. 30, 2025 | Jun. 30, 2025 | Jun. 30, 2025 | Dec. 31, 2024
Business Combination [Line Items] |  |  |  |  |
Common stock, shares issued (in shares) |  | 706,729,115 | 706,729,115 | 706,729,115 | 702,224,674
Treasury stock, shares (in shares) |  | 67,211,809 | 67,211,809 | 67,211,809 | 320,994,331
Preferred stock, shares issued (in shares) |  | 4,980,700 | 4,980,700 | 4,980,700 | 4,975,000
Preferred stock, value, issued |  | $ 0 | $ 0 | $ 0 | $ 0
Goodwill |  | 28,335 | 28,335 | 28,335 | $ 15,059
Series D Preferred Stock |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Per annum dividend rate | 6.125% |  |  |  |
Series P |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Per annum dividend rate | 6.125% |  |  |  |
Discover |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Common stock, shares issued (in shares) | 1.0192 |  |  |  |
Treasury stock, shares (in shares) | 256,497,213 |  |  |  |
Treasury stock, value | $ 50,600 |  |  |  |
Preferred stock, shares issued (in shares) | 10,700 |  |  |  |
Preferred stock, value, issued | $ 1,100 |  |  |  |
Business combination, stock-based compensation award | 136 |  |  |  |
Fair value of purchase consideration | 51,793 |  |  |  |
Launch and integration expenses |  | 299 | $ 409 | $ 643 |
Business combination, allowance for credit losses PCD loan | 8,800 |  |  |  |
Goodwill | $ 13,242 |  |  |  |
Business combination, pro-forma information, interest income from continuing operations |  | 1,700 |  |  |
Business combination, pro-forma information, non-interest income from continuing operations |  | 347 |  |  |
Business combination, pro forma information, pro forma income (loss) from continuing operations, after tax |  | $ (6,400) |  |  |
Discover | Series P |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Per annum dividend rate | 6.125% |  |  |  |
Preferred stock, shares issued (in shares) | 5,000 |  |  |  |
Discover | Discover |  |  |  |  |
Business Combination [Line Items] |  |  |  |  |
Common stock, shares issued (in shares) | 251,679,740 |  |  |  |

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