Mortgage Loans - TDRs with Sub Defaults (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans troubled debt restructurings subsequent default | contract	9,243
Restructured loans, subsequent default | $	$ 1,510
Single-family
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans troubled debt restructurings subsequent default | contract	9,243
Restructured loans, subsequent default | $	$ 1,510
Single-family | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans troubled debt restructurings subsequent default | contract	7,799
Restructured loans, subsequent default | $	$ 1,302
Single-family | 15-year or less, amortizing fixed-rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans troubled debt restructurings subsequent default | contract	489
Restructured loans, subsequent default | $	$ 37
Single-family | Adjustable-rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans troubled debt restructurings subsequent default | contract	33
Restructured loans, subsequent default | $	$ 5
Single-family | Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans troubled debt restructurings subsequent default | contract	922
Restructured loans, subsequent default | $	$ 166
Multifamily
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans troubled debt restructurings subsequent default | contract	0
Restructured loans, subsequent default | $	$ 0