Mortgage Loans - Loan Reclassifications (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Held-for-Investment | Single-family
Financing Receivable, Allowance for Credit Loss [Line Items]
UPB reclassified for-investment to held-for-sale	$ 1,577	$ 2,285
Valuation allowance (established) or reversed	0	0
Allowance for credit losses reversed or (established)	28	75
Held-for-Investment | Multifamily
Financing Receivable, Allowance for Credit Loss [Line Items]
UPB reclassified for-investment to held-for-sale	1,216	1,322
Valuation allowance (established) or reversed	(35)	(61)
Allowance for credit losses reversed or (established)	2	12
Held-for-Sale | Single-family
Financing Receivable, Allowance for Credit Loss [Line Items]
Valuation allowance (established) or reversed	25	19
UPB reclassified from held-for-sale to held-for-investment	436	233
Allowance for credit losses reversed or (established)	37	19
Held-for-Sale | Multifamily
Financing Receivable, Allowance for Credit Loss [Line Items]
Valuation allowance (established) or reversed	5	10
UPB reclassified from held-for-sale to held-for-investment	336	833
Allowance for credit losses reversed or (established)	$ (1)	$ 0