Investments (Details) - Table - AFS Securities (Amortized Cost & Fair Values) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
AFS Securities
Amortized Cost	$ 20,048	$ 20,144
Allowance for Credit Losses	(32)	(32)
Gross Unrealized Gains	173	158
Gross Unrealized Losses	(23)	(17)
Estimated Fair Value	20,166	20,253
U.S. Treasury obligations
AFS Securities
Amortized Cost	6,502	6,384
Allowance for Credit Losses	0	0
Gross Unrealized Gains	7	9
Gross Unrealized Losses	(1)	0
Estimated Fair Value	6,508	6,393
State housing agency obligations:
AFS Securities
Amortized Cost	54	42
Allowance for Credit Losses	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	0
Estimated Fair Value	53	42
MBS - GSEs
AFS Securities
Amortized Cost	12,617	12,819
Allowance for Credit Losses	0	0
Gross Unrealized Gains	139	118
Gross Unrealized Losses	(1)	0
Estimated Fair Value	12,755	12,937
PLRMBS
AFS Securities
Amortized Cost	875	899
Allowance for Credit Losses	(32)	(32)
Gross Unrealized Gains	27	31
Gross Unrealized Losses	(20)	(17)
Estimated Fair Value	850	881
MBS
AFS Securities
Amortized Cost	13,492	13,718
Allowance for Credit Losses	(32)	(32)
Gross Unrealized Gains	166	149
Gross Unrealized Losses	(21)	(17)
Estimated Fair Value	$ 13,605	$ 13,818

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