Investment Securities - Investment Available for Sale (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Investment securities available for sale:
Amortized Cost Basis	$ 97,536	$ 97,656
Allowance for Credit Losses	(3)	(3)
Gross Unrealized Gains	330	486
Gross Unrealized Losses	(7,243)	(7,088)
Fair Value	90,620	91,051
Investment securities held to maturity:
Investment securities held to maturity	1,694	0
Allowance for Credit Losses	0
Gross Unrealized Gains	1
Gross Unrealized Losses	(11)
Fair Value	1,684
U.S. Treasury securities
Investment securities available for sale:
Amortized Cost Basis	8,954	9,958
Allowance for Credit Losses	0	0
Gross Unrealized Gains	18	55
Gross Unrealized Losses	(6)	0
Fair Value	8,966	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	(2)
Fair Value	393
RMBS, Agency
Investment securities available for sale:
Amortized Cost Basis	75,708	75,561
Allowance for Credit Losses	0	0
Gross Unrealized Gains	222	322
Gross Unrealized Losses	(6,883)	(6,742)
Fair Value	69,047	69,141
Investment securities held to maturity:
Investment securities held to maturity	1,299
Allowance for Credit Losses	0
Gross Unrealized Gains	1
Gross Unrealized Losses	(9)
Fair Value	1,291
RMBS, Non-agency
Investment securities available for sale:
Amortized Cost Basis	515	525
Allowance for Credit Losses	(3)	(3)
Gross Unrealized Gains	57	67
Gross Unrealized Losses	(3)	(2)
Fair Value	566	587
Total RMBS
Investment securities available for sale:
Amortized Cost Basis	76,223	76,086
Allowance for Credit Losses	(3)	(3)
Gross Unrealized Gains	279	389
Gross Unrealized Losses	(6,886)	(6,744)
Fair Value	69,613	69,728
Agency CMBS
Investment securities available for sale:
Amortized Cost Basis	7,785	8,201
Allowance for Credit Losses	0	0
Gross Unrealized Gains	30	35
Gross Unrealized Losses	(344)	(344)
Fair Value	7,471	7,892
Other securities
Investment securities available for sale:
Amortized Cost Basis	4,574	3,411
Allowance for Credit Losses	0	0
Gross Unrealized Gains	3	7
Gross Unrealized Losses	(7)	0
Fair Value	4,570	3,418
Asset-backed Securities
Investment securities available for sale:
Fair Value	$ 2,400	$ 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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