Summary of Significant Accounting Policies (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2023	Dec. 31, 2022
Related Parties [Line Items]
Net worth	$ 73,700			$ 73,700
Increase in net worth	4,700	$ 5,000
TCCA fees	$ 860		$ 850	$ 2,571	$ 2,515
Basis points of each dollar of unpaid principal balance	0.042%			0.042%
Affordable Housing Program obligation	35.00%			35.00%
Acquired property	$ 1,700			$ 1,700			$ 1,600
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]
Total available funding from US Treasury pursuant to the senior preferred stock agreement	$ 113,900			$ 113,900
Aggregate liquidation preference of senior preferred stock	$ 190,500	$ 185,500		$ 190,500
Percentage of common shares attributable to warrants	79.90%			79.90%
Home Affordable Modification Program administrative expense reimbursements			$ 4	$ 6	$ 11
TCCA fees	$ 860		850	2,571	2,515
US Treasury | Forecast
Related Parties [Line Items]
Aggregate liquidation preference of senior preferred stock						$ 195,200
US Treasury | Other Expense
Related Parties [Line Items]
Affordable Housing Program assessments recognized	15		19	42	85
Affordable housing program assessments not remitted				42
US Treasury | Single-Family
Related Parties [Line Items]
Recognized TCCA fees that had not been remitted to Treasury as of period end	860			860
Federal Housing Finance Agency
Related Parties [Line Items]
FHFA assessment fees	39		30	118	93
Common Securitization Solutions
Related Parties [Line Items]
Capital contributed	13		$ 13	55	$ 51
US Treasury and Government
Related Parties [Line Items]
Aggregate funding received from US Treasury pursuant to the senior preferred stock purchase agreement	$ 119,800			$ 119,800