Debt - Long-Term Debt (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Debt Instrument [Line Items]
Long-term Debt	$ 163,745	$ 169,296
Held by Freddie Mac
Debt Instrument [Line Items]
Par Value Of Long Term Debt	167,455	172,694
Long-term Debt	$ 163,745	$ 169,296
Long-term debt weighted average effective rate	4.00%	4.15%
Long-Term Debt, Fair Value	$ 200	$ 200
Fixed Rate \| Held by Freddie Mac
Debt Instrument [Line Items]
Par Value Of Long Term Debt	104,647	92,236
Long-term Debt	$ 102,137	$ 90,104
Long-term debt weighted average effective rate	3.63%	3.62%
Fixed Rate \| Held by Freddie Mac \| Callable Medium Term Notes
Debt Instrument [Line Items]
Par Value Of Long Term Debt	$ 96,800	$ 84,400
Variable Rate \| Held by Freddie Mac
Debt Instrument [Line Items]
Par Value Of Long Term Debt	58,439	76,008
Long-term Debt	$ 58,421	$ 75,991
Long-term debt weighted average effective rate	4.58%	4.74%
Variable Rate \| Held by Freddie Mac \| Callable Medium Term Notes
Debt Instrument [Line Items]
Par Value Of Long Term Debt	$ 800	$ 700
Zero Coupon \| Held by Freddie Mac
Debt Instrument [Line Items]
Par Value Of Long Term Debt	3,904	3,904
Long-term Debt	$ 2,671	$ 2,610
Long-term debt weighted average effective rate	4.74%	4.73%
Other \| Held by Freddie Mac
Debt Instrument [Line Items]
Par Value Of Long Term Debt	$ 465	$ 546
Long-term Debt	$ 516	$ 591
Long-term debt weighted average effective rate	7.88%	8.95%