Fair Value Measurements - Unobservable Inputs Assumptions - Loans Held for Investment (Details) - Level 3 - Loans held for investment, at fair value	Sep. 30, 2024	Dec. 31, 2023
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Coupon	5.90%	5.90%
FICO	665	664
Loan-to-value (LTV)	78.00%	79.00%
Single family
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average percent	78.00%	79.00%
Manufactured housing
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average percent	3.00%	3.00%
Multi-family/mixed use/other
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average percent	19.00%	18.00%
Owner Occupied
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average percent	86.00%	86.00%
Investor
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average percent	9.00%	9.00%
Secondary
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average percent	5.00%	5.00%
Base Rate
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Coupon	5.70%	6.40%
FICO	640	640
Loan-to-value (LTV)	86.00%	86.00%