Concentration of Credit and Other Risks - Concentration of Credit Risk - Single-Family Mortgage Portfolio (Details) $ in Millions	Dec. 31, 2025 USD ($)
Concentration Risk [Line Items]
Single-Family serious delinquency rate	0.59%
West [Member]
Concentration Risk [Line Items]
Single-Family serious delinquency rate	0.46%
Northeast [Member]
Concentration Risk [Line Items]
Single-Family serious delinquency rate	0.61%
Southeast [Member]
Concentration Risk [Line Items]
Single-Family serious delinquency rate	0.67%
Southwest [Member]
Concentration Risk [Line Items]
Single-Family serious delinquency rate	0.63%
North Central [Member]
Concentration Risk [Line Items]
Single-Family serious delinquency rate	0.59%
CALIFORNIA
Concentration Risk [Line Items]
Single-Family serious delinquency rate	0.45%
TEXAS
Concentration Risk [Line Items]
Single-Family serious delinquency rate	0.71%
FLORIDA
Concentration Risk [Line Items]
Single-Family serious delinquency rate	0.80%
NEW YORK
Concentration Risk [Line Items]
Single-Family serious delinquency rate	0.81%
ILLINOIS
Concentration Risk [Line Items]
Single-Family serious delinquency rate	0.69%
All Other
Concentration Risk [Line Items]
Single-Family serious delinquency rate	0.55%
All Other | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, unpaid principal balance	$ 1,946,619
Unpaid principal balance, percent of portfolio	62.00%
Single-family UPB | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, unpaid principal balance	$ 3,155,981
Unpaid principal balance, percent of portfolio	100.00%
Single-family UPB | West [Member] | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, unpaid principal balance	$ 921,697
Unpaid principal balance, percent of portfolio	29.00%
Single-family UPB | Northeast [Member] | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, unpaid principal balance	$ 728,432
Unpaid principal balance, percent of portfolio	23.00%
Single-family UPB | Southeast [Member] | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, unpaid principal balance	$ 564,250
Unpaid principal balance, percent of portfolio	18.00%
Single-family UPB | Southwest [Member] | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, unpaid principal balance	$ 478,227
Unpaid principal balance, percent of portfolio	15.00%
Single-family UPB | North Central [Member] | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, unpaid principal balance	$ 463,375
Unpaid principal balance, percent of portfolio	15.00%
Single-family UPB | CALIFORNIA | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, unpaid principal balance	$ 509,813
Unpaid principal balance, percent of portfolio	16.00%
Single-family UPB | TEXAS | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, unpaid principal balance	$ 229,450
Unpaid principal balance, percent of portfolio	7.00%
Single-family UPB | FLORIDA | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, unpaid principal balance	$ 213,784
Unpaid principal balance, percent of portfolio	7.00%
Single-family UPB | NEW YORK | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, unpaid principal balance	$ 138,196
Unpaid principal balance, percent of portfolio	4.00%
Single-family UPB | ILLINOIS | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, unpaid principal balance	$ 118,119
Unpaid principal balance, percent of portfolio	4.00%