Investment Securities - Investment Available for Sale (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Investment securities available for sale:
Amortized Cost Basis	$ 96,954	$ 97,656
Allowance for Credit Losses	(3)	(3)
Gross Unrealized Gains	343	486
Gross Unrealized Losses	(7,253)	(7,088)
Fair Value	90,041	91,051
Investment securities held to maturity:
Investment securities held to maturity	2,737	0
Allowance for Credit Losses	0
Gross Unrealized Gains	1
Gross Unrealized Losses	(25)
Fair Value	2,713
U.S. Treasury securities
Investment securities available for sale:
Amortized Cost Basis	9,157	9,958
Allowance for Credit Losses	0	0
Gross Unrealized Gains	31	55
Gross Unrealized Losses	(12)	0
Fair Value	9,176	10,013
Investment securities held to maturity:
Investment securities held to maturity	395
Allowance for Credit Losses	0
Gross Unrealized Gains	0
Gross Unrealized Losses	(5)
Fair Value	390
RMBS, Agency
Investment securities available for sale:
Amortized Cost Basis	74,505	75,561
Allowance for Credit Losses	0	0
Gross Unrealized Gains	224	322
Gross Unrealized Losses	(6,880)	(6,742)
Fair Value	67,849	69,141
Investment securities held to maturity:
Investment securities held to maturity	2,342
Allowance for Credit Losses	0
Gross Unrealized Gains	1
Gross Unrealized Losses	(20)
Fair Value	2,323
RMBS, Non-agency
Investment securities available for sale:
Amortized Cost Basis	506	525
Allowance for Credit Losses	(3)	(3)
Gross Unrealized Gains	56	67
Gross Unrealized Losses	(2)	(2)
Fair Value	557	587
Total RMBS
Investment securities available for sale:
Amortized Cost Basis	75,011	76,086
Allowance for Credit Losses	(3)	(3)
Gross Unrealized Gains	280	389
Gross Unrealized Losses	(6,882)	(6,744)
Fair Value	68,406	69,728
Agency CMBS
Investment securities available for sale:
Amortized Cost Basis	7,890	8,201
Allowance for Credit Losses	0	0
Gross Unrealized Gains	29	35
Gross Unrealized Losses	(347)	(344)
Fair Value	7,572	7,892
Other securities
Investment securities available for sale:
Amortized Cost Basis	4,896	3,411
Allowance for Credit Losses	0	0
Gross Unrealized Gains	3	7
Gross Unrealized Losses	(12)	0
Fair Value	4,887	3,418
Asset-backed Securities
Investment securities available for sale:
Fair Value	$ 2,500	$ 1,900

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).

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