Investments Securities - Available-For-Sale Securities (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	$ 3,149	$ 3,815
Gross Unrealized Gains in Other Comprehensive Income	225	198
Gross Unrealized Losses in Other Comprehensive Income	(58)	(114)
Available-for-sale securities, at fair value	3,316	3,899
Accrued Interest Receivable	13	10
Agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	2,726	3,528
Gross Unrealized Gains in Other Comprehensive Income	16	4
Gross Unrealized Losses in Other Comprehensive Income	(40)	(100)
Available-for-sale securities, at fair value	2,702	3,432
Accrued Interest Receivable	6	7
Other mortgage-related securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	423	287
Gross Unrealized Gains in Other Comprehensive Income	209	194
Gross Unrealized Losses in Other Comprehensive Income	(18)	(14)
Available-for-sale securities, at fair value	614	467
Accrued Interest Receivable	$ 7	$ 3