v3.26.1
Fair Value (Fair Value Difference Between Fair Value and Remaining Contractual Principal Balance Outstanding) (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair Value Option, Principal Balance, Advances $ 5,109 $ 5,371
Fair Value of advances under the fair value option 5,151 5,441
Fair Value Over/(Under) Principal Balance, Advances 42 70
Consolidated obligation bonds    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Fair Value Option, Principal Balance, CO Bonds 370 360
Bonds, fair value under the fair value option 368 357
Fair Value Over/(Under) Principal Balance, CO Bonds $ (2) $ (3)