Investments (Trading Major Security Types) (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Debt and Equity Securities, FV-NI [Line Items]
Trading securities (includes $1,613 and $1,390 pledged as collateral that may be repledged)	$ 6,109	$ 6,303
US Treasury Securities [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading securities (includes $1,613 and $1,390 pledged as collateral that may be repledged)	5,914	6,104
U.S. obligations [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading securities (includes $1,613 and $1,390 pledged as collateral that may be repledged)	54	57
GSE obligations [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading securities (includes $1,613 and $1,390 pledged as collateral that may be repledged)	47	48
Other [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading securities (includes $1,613 and $1,390 pledged as collateral that may be repledged)	$ 94	$ 94