Segment Reporting - Segment Assets (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 3,497,598	$ 3,386,692
Operating segments | Single Family Guarantee Segment
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	3,156,290	3,104,174
Operating segments | Multifamily Segment
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	495,835	466,635
Operating segments | Operating segments and All Other
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	3,652,125	3,570,809
Reconciling items
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (154,527)	$ (184,117)