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Investment Securities (Narrative) (Details) | 3 Months Ended | 6 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Sep. 30, 2024 USD ($) $ / shares shares | Jun. 30, 2024 USD ($) $ / shares shares | Jun. 30, 2025 USD ($) | Jun. 30, 2024 USD ($) $ / shares shares | Dec. 31, 2024 USD ($) Rate | May 03, 2024 USD ($) shares | Mar. 31, 2024 USD ($) shares | Dec. 31, 2023 USD ($)
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Equity Securities without Readily Determinable Fair Value, Amount |  | $ 65,780,000 | $ 9,413,000 | $ 65,780,000 | $ 9,083,000 |  | $ 6,988,000 | $ 6,978,000
Percentage decrease requiring a review for impairment |  |  | 20.00% |  |  |  |  |
Fair value of securities on impairment watch list |  |  | $ 1,100,000,000 |  | 1,600,000,000 |  |  |
Debt Securities, Available-for-sale, Unrealized Loss Position |  |  | 6,462,218,000 |  | 8,134,911,000 |  |  |
Unrealized Loss on AFS Debt Securities |  |  | 796,304,000 |  | 994,534,000 |  |  |
AFS securities in loss position at period-end, change in unrealized loss |  |  | (198,200,000) |  |  |  |  |
Securities pledged as collateral |  |  | $ 6,900,000,000 |  | 6,900,000,000 |  |  |
Debt Securities, Available-for-Sale, Planned Sale, Amortized Cost |  |  |  |  | $ 1,200,000,000 |  |  |
Debt Securities, Available-for-Sale, Planned Sale, Yield | Rate |  |  |  |  | 2.10% |  |  |
Loss on Available for Sale debt securities portfolio repositioning |  |  |  |  | $ 179,100,000 |  |  |
Debt Securities, Available-for-Sale, Planned Sale, Reinvestment |  |  |  |  | $ 928,800,000 |  |  |
Debt Securities, Available-for-Sale, Planned Sale, Yield of Reinvestment | Rate |  |  |  |  | 4.60% |  |  |
Number of investments in a single issuer that exceed 10% of stockholder's equity |  |  | 0 |  |  |  |  |
No investment in a single issuer exceeds this percentage of stockholder's equity |  |  | 10.00% |  |  |  |  |
U.S. government and federal agency obligations |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
U.S. Treasury inflation-protected securities held, at fair value |  |  | $ 413,400,000 |  |  |  |  |
Debt Securities, Available-for-sale, Unrealized Loss Position |  |  | 982,542,000 |  | $ 1,846,004,000 |  |  |
Unrealized Loss on AFS Debt Securities |  |  | 12,749,000 |  | $ 41,859,000 |  |  |
Available-for-sale Securities [Member] |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Available-for-sale Securities, Losses realized on sales |  |  | (4,218,000) | 187,543,000 |  |  |  |
Equity Securities [Member] |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Equity Securities, FV-NI, Gain (Loss) |  | $ 178,164,000 | 1,777,000 | $ 178,306,000 |  |  |  |
Visa Class B-1 Shares |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Equity Securities without Readily Determinable Fair Value, Shares | shares |  |  |  |  |  |  | 823,447 |
Equity Securities without Readily Determinable Fair Value, Carrying Value |  |  |  |  |  |  | $ 0 |
Exchange Offer, Original Shares Held | shares |  |  |  |  |  |  | 823,447 |
Visa Class B-2 Shares |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Exchange Offer, Common Shares Received | shares |  |  |  |  |  | 411,723 |  |
Equity Securities without Readily Determinable Fair Value, Amount |  |  |  |  |  | $ 0 |  |
Visa Class A Shares |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Exchange Offer, Conversion Rate of Common Stock |  |  |  |  |  | 1.5875 |  |
Equity Securities Sold, Shares | shares | 218,000 | 436,000 |  | 436,000 |  |  |  |
Equity Securities Sold, Average Price | $ / shares | $ 260.56 | $ 274.91 |  | $ 274.91 |  |  |  |
Proceeds from Sale of Equity Securities | $ 56,800,000 | $ 119,800,000 |  |  |  |  |  |
Visa Class C Shares |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Exchange Offer, Common Shares Received | shares |  |  |  |  |  | 163,404 |  |
Private Equity Securities |  |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |  |
Other Securities, Loss realized on sales |  |  | (606,000) |  |  |  |  |
Fair value other securities adjustments, net |  |  | $ (4,100,000) |  |  |  |  |

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