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Investment Securities - Investment Available for Sale (Details) - USD ($) $ in Millions | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | $ 96,939 | $ 92,995
Allowance for Credit Losses | (3) | (4)
Gross Unrealized Gains | 361 | 148
Gross Unrealized Losses | (7,564) | (10,126)
Fair Value | 89,733 | 83,013
U.S. Treasury securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 8,613 | 6,114
Allowance for Credit Losses | 0 | 0
Gross Unrealized Gains | 28 | 5
Gross Unrealized Losses | (4) | (9)
Fair Value | 8,637 | 6,110
RMBS, Agency |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 75,246 | 74,177
Allowance for Credit Losses | 0 | 0
Gross Unrealized Gains | 218 | 57
Gross Unrealized Losses | (7,167) | (9,527)
Fair Value | 68,297 | 64,707
RMBS, Non-agency |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 536 | 567
Allowance for Credit Losses | (3) | (4)
Gross Unrealized Gains | 72 | 64
Gross Unrealized Losses | (3) | (6)
Fair Value | 602 | 621
Total RMBS |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 75,782 | 74,744
Allowance for Credit Losses | (3) | (4)
Gross Unrealized Gains | 290 | 121
Gross Unrealized Losses | (7,170) | (9,533)
Fair Value | 68,899 | 65,328
Agency CMBS |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 8,795 | 8,389
Allowance for Credit Losses | 0 | 0
Gross Unrealized Gains | 35 | 17
Gross Unrealized Losses | (390) | (581)
Fair Value | 8,440 | 7,825
Other securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 3,749 | 3,748
Allowance for Credit Losses | 0 | 0
Gross Unrealized Gains | 8 | 5
Gross Unrealized Losses | 0 | (3)
Fair Value | 3,757 | 3,750
Asset-backed Securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value | $ 1,800 | $ 2,000

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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-2 + Details
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