v3.25.3
Investments AFS - Schedule of Reconciliation Table (Details) - USD ($)
Sep. 30, 2025
Jun. 30, 2025
Dec. 31, 2024
Sep. 30, 2024
Jun. 30, 2024
Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]            
AFS Securities - Amortized Cost, $ 17,860,037,000   $ 18,207,176,000 [1]      
Balance, beginning of period 15,898,000 $ 15,653,000 14,160,000 $ 13,049,000 $ 13,938,000 $ 11,988,000
Gross Unrealized Gains 58,844,000   57,341,000      
Gross Unrealized Losses (70,689,000)   (86,514,000)      
Available-for-Sale - Accrued Interest 57,500,000   55,000,000.0      
Fair Value $ 17,832,294,000   $ 18,163,843,000      
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration] Accrued interest receivable   Accrued interest receivable      
GSE obligations            
Debt Securities, Available-for-sale [Line Items]            
AFS Securities - Amortized Cost, [1] $ 847,827,000   $ 890,230,000      
Balance, beginning of period 0   0      
Gross Unrealized Gains 15,815,000   18,885,000      
Gross Unrealized Losses (1,156,000)   (1,991,000)      
Fair Value 862,486,000   907,124,000      
State or local agency obligations [Member]            
Debt Securities, Available-for-sale [Line Items]            
AFS Securities - Amortized Cost, [1] 181,085,000   182,220,000      
Balance, beginning of period 0   0      
Gross Unrealized Gains 11,000   0      
Gross Unrealized Losses (9,095,000)   (12,884,000)      
Fair Value 172,001,000   169,336,000      
Non-MBS [Member]            
Debt Securities, Available-for-sale [Line Items]            
AFS Securities - Amortized Cost, [1] 4,979,867,000   5,184,843,000      
Balance, beginning of period 0   0      
Gross Unrealized Gains 19,546,000   23,168,000      
Gross Unrealized Losses (12,173,000)   (18,596,000)      
Fair Value 4,987,240,000   5,189,415,000      
U.S. obligations single-family            
Debt Securities, Available-for-sale [Line Items]            
AFS Securities - Amortized Cost, [1] 1,407,829,000   1,720,328,000      
Balance, beginning of period 0   0      
Gross Unrealized Gains 1,916,000   4,404,000      
Gross Unrealized Losses (8,485,000)   (12,348,000)      
Fair Value 1,401,260,000   1,712,384,000      
Private label MBS [Member]            
Debt Securities, Available-for-sale [Line Items]            
AFS Securities - Amortized Cost, [1] 118,540,000   124,140,000      
Balance, beginning of period 15,898,000   14,160,000      
Gross Unrealized Gains 4,366,000   5,235,000      
Gross Unrealized Losses (1,841,000)   (1,720,000)      
Fair Value 105,167,000   113,495,000      
MBS [Member]            
Debt Securities, Available-for-sale [Line Items]            
AFS Securities - Amortized Cost, [1] 12,880,170,000   13,022,333,000      
Balance, beginning of period 15,898,000   14,160,000      
Gross Unrealized Gains 39,298,000   34,173,000      
Gross Unrealized Losses (58,516,000)   (67,918,000)      
Fair Value 12,845,054,000   12,974,428,000      
U.S. Treasury obligations            
Debt Securities, Available-for-sale [Line Items]            
AFS Securities - Amortized Cost, 3,950,955,000   4,112,393,000      
Balance, beginning of period 0   0      
Gross Unrealized Gains 3,720,000   4,283,000      
Gross Unrealized Losses (1,922,000)   (3,721,000)      
Fair Value 3,952,753,000   4,112,955,000      
Single Family [Member] | GSE MBS [Member]            
Debt Securities, Available-for-sale [Line Items]            
AFS Securities - Amortized Cost, [1] 4,993,695,000   4,634,380,000      
Balance, beginning of period 0   0      
Gross Unrealized Gains 4,822,000   5,162,000      
Gross Unrealized Losses (40,158,000)   (41,657,000)      
Fair Value 4,958,359,000   4,597,885,000      
Multifamily [Member] | GSE MBS [Member]            
Debt Securities, Available-for-sale [Line Items]            
AFS Securities - Amortized Cost, [1] 6,360,106,000   6,543,485,000      
Balance, beginning of period 0   0      
Gross Unrealized Gains 28,194,000   19,372,000      
Gross Unrealized Losses (8,032,000)   (12,193,000)      
Fair Value $ 6,380,268,000   $ 6,550,664,000      
[1] Includes adjustments made to the cost basis of investments for accretion, amortization and/or fair value hedge accounting adjustments, and excludes accrued interest receivable of $57.5 million at September 30, 2025 and $55.0 million at December 31, 2024.