v3.26.1
Estimated Fair Values (Fair Value Measured on Recurring and Nonrecurring Basis) (Details) - USD ($)
Jun. 30, 2026
Dec. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets $ 344,620,000 $ 350,117,000
Derivative Asset, Subject to Master Netting Arrangement, Gross Liability and Collateral, Obligation to Return Cash, Offset [1],[2] 235,783,000 271,014,000
Derivative liabilities 7,032,000 1,994,000
Derivative Liability, Subject to Master Netting Arrangement, Gross Asset and Collateral, Right to Reclaim Cash, Offset [2] (72,808,000) (124,837,000) [1]
Fair Value 20,595,928,000 18,189,327,000
Fair Value, Inputs, Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 0 0
Derivative assets 0 0
Derivative liabilities 0 0
Fair Value 0 0
Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 113,575,000 119,676,000
Derivative assets 108,837,000 79,103,000
Derivative liabilities 79,840,000 126,831,000
Fair Value 20,500,323,000 18,087,199,000
Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 0 0
Derivative assets 0 0
Derivative liabilities 0 0
Fair Value 95,605,000 102,128,000
Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Asset, Subject to Master Netting Arrangement, Gross Liability and Collateral, Obligation to Return Cash, Offset 235,783,000 271,014,000
Derivative Liability, Subject to Master Netting Arrangement, Gross Asset and Collateral, Right to Reclaim Cash, Offset (72,808,000) [1] (124,837,000)
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 0 0
AFS Securities 0 0
Derivative assets 0 0
Derivative liabilities 0  
Total assets at fair value 0 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 113,575,000 119,676,000
AFS Securities 20,500,323,000 18,087,199,000
Derivative assets 108,837,000 79,103,000
Derivative liabilities 79,840,000 126,831,000
Total assets at fair value 20,722,735,000 18,285,978,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 0 0
AFS Securities 95,605,000 102,128,000
Derivative assets 0 0
Derivative liabilities 0 0
Total assets at fair value 95,605,000 102,128,000
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Mortgage loans held for portfolio 5,399,000 10,751,000
REO - FV 906,000 328,000
Total assets at fair value 6,305,000 11,079,000
Interest Rate Swap [Member] | Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Asset, Subject to Master Netting Arrangement, Gross Liability and Collateral, Obligation to Return Cash, Offset 235,783,000 271,014,000
Derivative Liability, Subject to Master Netting Arrangement, Gross Asset and Collateral, Right to Reclaim Cash, Offset (72,808,000) (124,837,000)
Interest Rate Swap [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Interest Rate Swap [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 108,830,000 79,097,000
Derivative liabilities 78,890,000 126,233,000
Interest Rate Swap [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
U.S. Treasury obligations    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 5,105,478,000 4,912,280,000
U.S. Treasury obligations | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 5,105,478,000 4,912,280,000
GSE obligations    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 113,575,000 119,676,000
Fair Value 775,565,000 834,063,000
GSE obligations | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 0 0
AFS Securities 0 0
GSE obligations | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 113,575,000 119,676,000
AFS Securities 775,565,000 834,063,000
GSE obligations | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 0 0
AFS Securities 0 0
State or local agency obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 175,902,000 174,833,000
State or local agency obligations [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 0  
Fair Value   0
State or local agency obligations [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 175,902,000  
Fair Value   174,833,000
State or local agency obligations [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 0  
Fair Value   0
U.S. obligations single-family    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 1,447,418,000 1,303,882,000
U.S. obligations single-family | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 0  
Fair Value   0
U.S. obligations single-family | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 1,447,418,000  
Fair Value   1,303,882,000
U.S. obligations single-family | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 0  
Fair Value   0
Private label MBS [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 95,605,000 102,128,000
Private label MBS [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 0  
Fair Value   0
Private label MBS [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 0  
Fair Value   0
Private label MBS [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 95,605,000  
Fair Value   102,128,000
Mortgage Receivable [Member] | Forward Contracts [Member] | Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Asset, Subject to Master Netting Arrangement, Gross Liability and Collateral, Obligation to Return Cash, Offset 0 0
Mortgage Receivable [Member] | Forward Contracts [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 0
Mortgage Receivable [Member] | Forward Contracts [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 7,000 6,000
Derivative liabilities 950,000 598,000
Mortgage Receivable [Member] | Forward Contracts [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 0 0
Derivative liabilities 0  
Estimate of Fair Value Measurement [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 113,575,000 119,676,000
Derivative assets 344,620,000 350,117,000
Derivative liabilities 7,032,000 1,994,000
Fair Value 20,595,928,000 18,189,327,000
Estimate of Fair Value Measurement [Member] | Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 113,575,000 119,676,000
AFS Securities 20,595,928,000 18,189,327,000
Derivative assets 344,620,000 350,117,000
Derivative liabilities 7,032,000 1,994,000
Total assets at fair value 21,054,123,000 18,659,120,000
Estimate of Fair Value Measurement [Member] | Fair Value, Nonrecurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Mortgage loans held for portfolio 5,399,000 10,751,000
REO - FV 906,000 328,000
Total assets at fair value 6,305,000 11,079,000
Estimate of Fair Value Measurement [Member] | Interest Rate Swap [Member] | Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 344,613,000 350,111,000
Derivative liabilities 6,082,000 1,396,000
Estimate of Fair Value Measurement [Member] | U.S. Treasury obligations | Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 5,105,478,000 4,912,280,000
Estimate of Fair Value Measurement [Member] | GSE obligations | Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading securities 113,575,000 119,676,000
AFS Securities 775,565,000 834,063,000
Estimate of Fair Value Measurement [Member] | State or local agency obligations [Member] | Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 175,902,000 174,833,000
Estimate of Fair Value Measurement [Member] | U.S. obligations single-family | Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 1,447,418,000 1,303,882,000
Estimate of Fair Value Measurement [Member] | Private label MBS [Member] | Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 95,605,000 102,128,000
Estimate of Fair Value Measurement [Member] | Mortgage Receivable [Member] | Forward Contracts [Member] | Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets 7,000 6,000
Derivative liabilities 950,000 598,000
Single Family [Member] | GSE MBS [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 5,852,554,000 4,547,773,000
Single Family [Member] | GSE MBS [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 0  
Fair Value   0
Single Family [Member] | GSE MBS [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 5,852,554,000  
Fair Value   4,547,773,000
Single Family [Member] | GSE MBS [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 0  
Single Family [Member] | Estimate of Fair Value Measurement [Member] | GSE MBS [Member] | Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 5,852,554,000 4,547,773,000
Multifamily [Member] | GSE MBS [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 7,143,406,000 6,314,368,000
Multifamily [Member] | GSE MBS [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 0  
Fair Value   0
Multifamily [Member] | GSE MBS [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 7,143,406,000  
Fair Value   6,314,368,000
Multifamily [Member] | GSE MBS [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities 0  
Fair Value   0
Multifamily [Member] | Estimate of Fair Value Measurement [Member] | GSE MBS [Member] | Fair Value, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
AFS Securities $ 7,143,406,000 $ 6,314,368,000
[1] Amounts represent the application of the netting requirements that allow the Bank to settle positive and negative positions and also cash collateral and related accrued interest held or placed by the Bank with the same clearing agent and/or counterparties.
[2] Amounts represent the application of the netting requirements that allow the Bank to settle positive and negative positions and also cash collateral and related accrued interest held or placed by the Bank with the same clearing agent and/or counterparties. Cash collateral posted including accrued interest was $350.1 million for June 30, 2026 and $411.3 million for December 31, 2025. Cash collateral received was $41.5 million for June 30, 2026 and $15.5 million for December 31, 2025