Mortgage Loans - Amortized Cost Basis of Held-for-Investment Loans by Payment Status (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 3,291,359	$ 3,177,386
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Non-Accrual with no allowance	832	578
Mortgage Loans in Process of Foreclosure, Amount	4,000	2,600
20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,844,612	2,771,770
Non-Accrual with no allowance	662	465
15-year or less, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	268,681	294,400
Non-Accrual with no allowance	7	5
Adjustable-rate and other
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	32,473	26,662
Non-Accrual with no allowance	31	33
Single-family
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	3,145,766	3,092,832
Non-Accrual with no allowance	700	503
Multifamily
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	145,593	84,554
Non-Accrual with no allowance	132	75
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	3,237,133	3,124,850
Financial Asset, Not Past Due | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Total	2,793,168	2,722,336
Financial Asset, Not Past Due | 15-year or less, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Total	266,741	292,207
Financial Asset, Not Past Due | Adjustable-rate and other
Financing Receivable, Past Due [Line Items]
Total	31,880	26,019
Financial Asset, Not Past Due | Single-family
Financing Receivable, Past Due [Line Items]
Total	3,091,789	3,040,562
Financial Asset, Not Past Due | Multifamily
Financing Receivable, Past Due [Line Items]
Total	145,344	84,288
One month past due
Financing Receivable, Past Due [Line Items]
Total	28,830	28,863
One month past due | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Total	27,286	27,090
One month past due | 15-year or less, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Total	1,196	1,404
One month past due | Adjustable-rate and other
Financing Receivable, Past Due [Line Items]
Total	291	309
One month past due | Single-family
Financing Receivable, Past Due [Line Items]
Total	28,773	28,803
One month past due | Multifamily
Financing Receivable, Past Due [Line Items]
Total	57	60
Two months past due
Financing Receivable, Past Due [Line Items]
Total	8,257	8,060
Two months past due | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Total	7,892	7,588
Two months past due | 15-year or less, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Total	276	291
Two months past due | Adjustable-rate and other
Financing Receivable, Past Due [Line Items]
Total	87	101
Two months past due | Single-family
Financing Receivable, Past Due [Line Items]
Total	8,255	7,980
Two months past due | Multifamily
Financing Receivable, Past Due [Line Items]
Total	2	80
Three months or more past due or in foreclosure
Financing Receivable, Past Due [Line Items]
Total	17,139	15,613
Three months or more past due or in foreclosure | 20- and 30-year or more, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Total	16,266	14,756
Three months or more past due or in foreclosure | 15-year or less, amortizing fixed-rate
Financing Receivable, Past Due [Line Items]
Total	468	498
Three months or more past due or in foreclosure | Adjustable-rate and other
Financing Receivable, Past Due [Line Items]
Total	215	233
Three months or more past due or in foreclosure | Single-family
Financing Receivable, Past Due [Line Items]
Total	16,949	15,487
Three months or more past due or in foreclosure | Multifamily
Financing Receivable, Past Due [Line Items]
Total	$ 190	$ 126