Summary of Significant Accounting Policies (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Sep. 30, 2022
Related Parties [Line Items]
Net worth	$ 56,400		$ 56,400
Increase in net worth	4,600
TCCA fees	$ 841	$ 758	$ 1,665	$ 1,489
Basis points of each dollar of unpaid principal balance	0.042%		0.042%
Affordable Housing Program obligation	35.00%		35.00%
Weighted average number of contingently issuable shares (shares)	4,700	4,700	4,700	4,700
Incremental common shares attributable to dilutive effect of conversion of preferred stock (in shares)	26	26	26	26
US Treasury
Related Parties [Line Items]
Aggregate funding received from US Treasury pursuant to the senior preferred stock purchase agreement	$ 119,800		$ 119,800
Total available funding from US Treasury pursuant to the senior preferred stock agreement	113,900		113,900
Aggregate liquidation preference of senior preferred stock	$ 173,300		$ 173,300
Percentage of common shares attributable to warrants	79.90%		79.90%
Home Affordable Modification Program administrative expense reimbursements	$ 3	$ 5	$ 7	$ 9
TCCA, increase of guarantee fee rate	0.10%		0.10%
TCCA fees	$ 841	758	$ 1,665	1,489
US Treasury | Other Expense
Related Parties [Line Items]
Affordable Housing Program assessments recognized	28	57	66	119
Affordable housing program assessments not remitted			66
US Treasury | Single Family
Related Parties [Line Items]
Recognized TCCA fees that had not been remitted to Treasury as of period end	(841)		(841)
US Treasury | Forecast
Related Parties [Line Items]
Aggregate liquidation preference of senior preferred stock					$ 177,900
Federal Housing Finance Agency
Related Parties [Line Items]
FHFA assessment fees	31	35	63	72
Common Securitization Solutions
Related Parties [Line Items]
Capital contributed	$ 16	$ 18	$ 38	$ 45