Mortgage Loans - Loans Purchased and Sold (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Single-family | Held-for-Investment
Financing Receivable, Allowance for Credit Loss [Line Items]
Purchase	$ 388,665	$ 346,408	$ 299,886
Single-family | Held-for-Sale
Financing Receivable, Allowance for Credit Loss [Line Items]
Sale of held-for-sale loans	2,676	2,072	1,253
Multifamily | Held-for-Investment
Financing Receivable, Allowance for Credit Loss [Line Items]
Purchase	65,616	30,003	16,814
Multifamily | Held-for-Sale
Financing Receivable, Allowance for Credit Loss [Line Items]
Purchase	7,734	31,712	29,415
Sale of held-for-sale loans	$ 17,080	$ 27,883	$ 34,034