Mortgage Loans - Loans in Mortgage Portfolio (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Loans in Mortgage Portfolio [Line Items]
Total UPB of mortgage loans	$ 4,093,384		$ 4,095,866
Cost basis and fair value adjustments, net	30,273		31,811
Allowance for loan losses for HFI loans	(8,357)	$ (7,532)	(8,364)
Total mortgage loans	4,115,300		4,119,313
Accrued interest receivable, net	11,915		11,689
Single-family
Loans in Mortgage Portfolio [Line Items]
Total UPB of mortgage loans	3,560,543		3,570,904
Purchase of HFI loans:	98,465	63,627
Amortized cost	0	510
Lower of cost or fair value adjustment at time of redesignation	0	(69)
Allowance reversed at time of redesignation	0	17
Multifamily
Loans in Mortgage Portfolio [Line Items]
Total UPB of mortgage loans	532,841		524,962
Purchase of HFI loans:	16,852	$ 11,514
Mortgage loans
Loans in Mortgage Portfolio [Line Items]
Accrued interest receivable, net	$ 11,400		$ 11,300

Financing Receivable, Transfer to Held-for-Sale, Allowance for Credit Loss, Adjustment, Other

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Mortgage Loans, Cost Basis and Fair Value Adjustments, Net

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Represents principal amount outstanding of mortgage loans.

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Amount, after allowance for credit loss, of accrued interest on financing receivable.

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Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

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Amount of financing receivable reclassified to held-for-sale.

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Amount of increase in financing receivable from purchase. Excludes net investment in lease.

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Amount of expense reversal of allowance for credit loss on financing receivable transferred to held-for-sale classification.

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The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

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