Mortgage Loans - Mortgage Loans (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivables [Line Items]
UPB of mortgage loans - HFS	$ 1,244	$ 16,249
Cost basis and fair value adjustments, net HFS	(230)	(689)
Total held-for-sale loans, net	1,014	15,560
UPB of mortgage loans - HFI	3,271,069	3,150,627
Cost basis adjustment HFI	26,965	28,476
Allowance for loan losses	(7,968)	(6,774)
Total held-for-investment mortgage loans, net	3,290,066	3,172,329
Total mortgage loans, net	3,291,080	3,187,889
Hedged Asset, Fair Value Hedge, Last-of-Layer, Cumulative Increase (Decrease)	(300)	(700)
Mortgage loans FVO held-for-investment	7,005	2,413
Single-family
Accounts, Notes, Loans and Financing Receivables [Line Items]
UPB of mortgage loans - HFS	1,108	2,984
Cost basis and fair value adjustments, net HFS	(216)	(586)
Total held-for-sale loans, net	892	2,398
UPB of mortgage loans - HFI	3,117,945	3,063,211
Cost basis adjustment HFI	27,491	28,926
Allowance for loan losses	(7,297)	(6,381)
Total held-for-investment mortgage loans, net	3,138,139	3,085,756
Total mortgage loans, net	3,139,031	3,088,154
Multifamily
Accounts, Notes, Loans and Financing Receivables [Line Items]
UPB of mortgage loans - HFS	136	13,265
Cost basis and fair value adjustments, net HFS	(14)	(103)
Total held-for-sale loans, net	122	13,162
UPB of mortgage loans - HFI	153,124	87,416
Cost basis adjustment HFI	(526)	(450)
Allowance for loan losses	(671)	(393)
Total held-for-investment mortgage loans, net	151,927	86,573
Total mortgage loans, net	$ 152,049	$ 99,735