v3.26.1
Concentration of Credit and Other Risks - Concentration of Credit Risk - Multifamily Mortgage Portfolio (Details)(Details)
$ in Millions
Jun. 30, 2026
USD ($)
Concentration Risk [Line Items]  
Multifamily Delinquency Rate 0.51%
Northeast  
Concentration Risk [Line Items]  
Multifamily Delinquency Rate 0.92%
West  
Concentration Risk [Line Items]  
Multifamily Delinquency Rate 0.24%
Southeast  
Concentration Risk [Line Items]  
Multifamily Delinquency Rate 0.19%
Southwest  
Concentration Risk [Line Items]  
Multifamily Delinquency Rate 0.72%
North Central  
Concentration Risk [Line Items]  
Multifamily Delinquency Rate 0.37%
California  
Concentration Risk [Line Items]  
Multifamily Delinquency Rate 0.25%
Texas  
Concentration Risk [Line Items]  
Multifamily Delinquency Rate 0.74%
Florida  
Concentration Risk [Line Items]  
Multifamily Delinquency Rate 0.12%
New York  
Concentration Risk [Line Items]  
Multifamily Delinquency Rate 2.14%
Georgia  
Concentration Risk [Line Items]  
Multifamily Delinquency Rate 0.19%
All Other  
Concentration Risk [Line Items]  
Multifamily Delinquency Rate 0.37%
Geographic Concentration Risk | All Other  
Concentration Risk [Line Items]  
Portfolio UPB $ 1,960,734
Unpaid Principal Balance, Percent Of Portfolio 62.00%
Geographic Concentration Risk | Multifamily Unpaid Principal Balance [Member]  
Concentration Risk [Line Items]  
Portfolio UPB $ 504,970
Unpaid Principal Balance, Percent Of Portfolio 100.00%
Geographic Concentration Risk | Multifamily Unpaid Principal Balance [Member] | Northeast  
Concentration Risk [Line Items]  
Portfolio UPB $ 129,249
Unpaid Principal Balance, Percent Of Portfolio 26.00%
Geographic Concentration Risk | Multifamily Unpaid Principal Balance [Member] | West  
Concentration Risk [Line Items]  
Portfolio UPB $ 116,794
Unpaid Principal Balance, Percent Of Portfolio 23.00%
Geographic Concentration Risk | Multifamily Unpaid Principal Balance [Member] | Southeast  
Concentration Risk [Line Items]  
Portfolio UPB $ 107,410
Unpaid Principal Balance, Percent Of Portfolio 21.00%
Geographic Concentration Risk | Multifamily Unpaid Principal Balance [Member] | Southwest  
Concentration Risk [Line Items]  
Portfolio UPB $ 97,901
Unpaid Principal Balance, Percent Of Portfolio 19.00%
Geographic Concentration Risk | Multifamily Unpaid Principal Balance [Member] | North Central  
Concentration Risk [Line Items]  
Portfolio UPB $ 53,616
Unpaid Principal Balance, Percent Of Portfolio 11.00%
Geographic Concentration Risk | Multifamily Unpaid Principal Balance [Member] | California  
Concentration Risk [Line Items]  
Portfolio UPB $ 62,776
Unpaid Principal Balance, Percent Of Portfolio 12.00%
Geographic Concentration Risk | Multifamily Unpaid Principal Balance [Member] | Texas  
Concentration Risk [Line Items]  
Portfolio UPB $ 61,184
Unpaid Principal Balance, Percent Of Portfolio 12.00%
Geographic Concentration Risk | Multifamily Unpaid Principal Balance [Member] | Florida  
Concentration Risk [Line Items]  
Portfolio UPB $ 46,035
Unpaid Principal Balance, Percent Of Portfolio 9.00%
Geographic Concentration Risk | Multifamily Unpaid Principal Balance [Member] | New York  
Concentration Risk [Line Items]  
Portfolio UPB $ 40,673
Unpaid Principal Balance, Percent Of Portfolio 8.00%
Geographic Concentration Risk | Multifamily Unpaid Principal Balance [Member] | Georgia  
Concentration Risk [Line Items]  
Portfolio UPB $ 22,200
Unpaid Principal Balance, Percent Of Portfolio 4.00%
Geographic Concentration Risk | Multifamily Unpaid Principal Balance [Member] | All Other  
Concentration Risk [Line Items]  
Portfolio UPB $ 272,102
Unpaid Principal Balance, Percent Of Portfolio 55.00%