v3.26.1
Fair Value of Financial Instruments - Schedule of Quantitative Information Regarding Significant and Unobservable Inputs Used in the Valuation of Level 3 Assets and Liabilities Measured at Fair Value (Details)
Mar. 31, 2026
USD ($)
month
Dec. 31, 2025
USD ($)
Mar. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Equity investments $ 23,468,000 $ 24,711,000    
Mortgage servicing rights 19,965,000 20,893,000 $ 20,297,000 $ 21,003,000
90 Days or greater past due        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Fair value 0 0    
Equity investments        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Equity investments 23,468,000 24,711,000    
Level 3        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, at fair value 4,619,634,000      
Equity investments 23,468,000 24,711,000    
Mortgage servicing rights 19,965,000 20,893,000    
Level 3 | Equity investments        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Equity investments 23,468,000      
Level 3 | MSRs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Mortgage servicing rights 19,965,000      
Level 3 | IRLCs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Derivative asset, estimated fair value $ 1,155,000      
Level 3 | Default rate | Valuation Technique, Discounted Cash Flow | Weighted Average | MSRs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Servicing asset, measurement input 0.026      
Level 3 | Default rate | Valuation Technique, Discounted Cash Flow | Minimum | MSRs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Servicing asset, measurement input 0      
Level 3 | Default rate | Valuation Technique, Discounted Cash Flow | Maximum | MSRs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Servicing asset, measurement input 0.420      
Level 3 | Yield | Valuation Technique, Discounted Cash Flow | Weighted Average | MSRs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Servicing asset, measurement input 0.122      
Level 3 | Yield | Valuation Technique, Discounted Cash Flow | Minimum | MSRs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Servicing asset, measurement input 0.105      
Level 3 | Yield | Valuation Technique, Discounted Cash Flow | Maximum | MSRs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Servicing asset, measurement input 0.155      
Level 3 | Discount rate | Valuation Technique, Discounted Cash Flow | Weighted Average | Equity investments        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Equity method investment, measurement input 0.158      
Level 3 | Discount rate | Valuation Technique, Discounted Cash Flow | Minimum | Equity investments        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Equity method investment, measurement input 0.150      
Level 3 | Discount rate | Valuation Technique, Discounted Cash Flow | Maximum | Equity investments        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Equity method investment, measurement input 0.175      
Level 3 | Months to assumed redemption | Valuation Technique, Discounted Cash Flow | Weighted Average | Equity investments        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Equity method investment, measurement input | month 14.8      
Level 3 | Months to assumed redemption | Valuation Technique, Discounted Cash Flow | Minimum | Equity investments        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Equity method investment, measurement input | month 2      
Level 3 | Months to assumed redemption | Valuation Technique, Discounted Cash Flow | Maximum | Equity investments        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Equity method investment, measurement input | month 26      
Level 3 | Lifetime voluntary prepayment rate | Valuation Technique, Discounted Cash Flow | Weighted Average | MSRs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Servicing asset, measurement input 0.094      
Level 3 | Lifetime voluntary prepayment rate | Valuation Technique, Discounted Cash Flow | Minimum | MSRs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Servicing asset, measurement input 0.001      
Level 3 | Lifetime voluntary prepayment rate | Valuation Technique, Discounted Cash Flow | Maximum | MSRs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Servicing asset, measurement input 0.285      
Level 3 | Pull-through rate | Valuation Technique, Probability-Weighted Expected Cash Flow | Weighted Average | IRLCs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Derivative asset, measurement Input 0.831      
Level 3 | Pull-through rate | Valuation Technique, Probability-Weighted Expected Cash Flow | Minimum | IRLCs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Derivative asset, measurement Input 0.826      
Level 3 | Pull-through rate | Valuation Technique, Probability-Weighted Expected Cash Flow | Maximum | IRLCs        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Derivative asset, measurement Input 0.856      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Valuation Technique, Discounted Cash Flow        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, at fair value $ 3,135,736,000      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Valuation Technique, Liquidation Model        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, at fair value 109,915,000      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Valuation Technique, Transaction Price        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, at fair value $ 235,916,000      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Lifetime CPR | Valuation Technique, Discounted Cash Flow | Weighted Average        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.109      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Lifetime CPR | Valuation Technique, Discounted Cash Flow | Minimum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Lifetime CPR | Valuation Technique, Discounted Cash Flow | Maximum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.471      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Default rate | Valuation Technique, Discounted Cash Flow | Weighted Average        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.007      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Default rate | Valuation Technique, Discounted Cash Flow | Minimum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Default rate | Valuation Technique, Discounted Cash Flow | Maximum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.215      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Loss severity | Valuation Technique, Discounted Cash Flow | Weighted Average        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.122      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Loss severity | Valuation Technique, Discounted Cash Flow | Minimum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Loss severity | Valuation Technique, Discounted Cash Flow | Maximum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 1.000      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Yield | Valuation Technique, Discounted Cash Flow | Weighted Average        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.065      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Yield | Valuation Technique, Discounted Cash Flow | Minimum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.037      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Yield | Valuation Technique, Discounted Cash Flow | Maximum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.334      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Yield | Valuation Technique, Liquidation Model | Weighted Average        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.088      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Yield | Valuation Technique, Liquidation Model | Minimum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.075      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Yield | Valuation Technique, Liquidation Model | Maximum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.643      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Annual home price appreciation/(depreciation) | Valuation Technique, Liquidation Model | Weighted Average        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.001      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Annual home price appreciation/(depreciation) | Valuation Technique, Liquidation Model | Minimum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Annual home price appreciation/(depreciation) | Valuation Technique, Liquidation Model | Maximum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 0.058      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Liquidation timeline (months) | Valuation Technique, Liquidation Model | Weighted Average        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input | month 17      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Liquidation timeline (months) | Valuation Technique, Liquidation Model | Minimum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input | month 9      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Liquidation timeline (months) | Valuation Technique, Liquidation Model | Maximum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input | month 54      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Property value | Valuation Technique, Liquidation Model | Weighted Average        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 1,740,000      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Property value | Valuation Technique, Liquidation Model | Minimum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 28,000      
Level 3 | Residential loans, residential loans held in securitization trusts and residential loans held for sale | Property value | Valuation Technique, Liquidation Model | Maximum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, measurement input 13,900,000      
Level 3 | Multi-family loans, at fair value        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, at fair value $ 55,910,000      
Level 3 | Multi-family loans, at fair value | Discount rate | Valuation Technique, Discounted Cash Flow | Weighted Average        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Financial instruments owned, measurement input 0.123      
Level 3 | Multi-family loans, at fair value | Discount rate | Valuation Technique, Discounted Cash Flow | Minimum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Financial instruments owned, measurement input 0.115      
Level 3 | Multi-family loans, at fair value | Discount rate | Valuation Technique, Discounted Cash Flow | Maximum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Financial instruments owned, measurement input 0.135      
Level 3 | Multi-family loans, at fair value | Months to assumed redemption | Valuation Technique, Discounted Cash Flow | Weighted Average        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Financial instruments owned, measurement input | month 20.4      
Level 3 | Multi-family loans, at fair value | Months to assumed redemption | Valuation Technique, Discounted Cash Flow | Minimum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Financial instruments owned, measurement input | month 3      
Level 3 | Multi-family loans, at fair value | Months to assumed redemption | Valuation Technique, Discounted Cash Flow | Maximum        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Financial instruments owned, measurement input | month 34      
Level 3 | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Loans receivable, at fair value $ 1,138,067,000      
Variable interest entity, primary beneficiary, maximum loss exposure, amount 146,700,000 $ 151,500,000    
Level 3 | Consolidated SLST | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Multi-family CDOs, at fair value $ 983,717,000      
Level 3 | Consolidated SLST | Loss severity | Valuation Technique, Discounted Cash Flow | Weighted Average | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Debt, measurement input 0.152      
Level 3 | Consolidated SLST | Loss severity | Valuation Technique, Discounted Cash Flow | Minimum | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Debt, measurement input 0.003      
Level 3 | Consolidated SLST | Loss severity | Valuation Technique, Discounted Cash Flow | Maximum | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Debt, measurement input 0.266      
Level 3 | Consolidated SLST | Yield | Valuation Technique, Discounted Cash Flow | Weighted Average | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Debt, measurement input 0.052      
Level 3 | Consolidated SLST | Yield | Valuation Technique, Discounted Cash Flow | Minimum | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Debt, measurement input 0.046      
Level 3 | Consolidated SLST | Yield | Valuation Technique, Discounted Cash Flow | Maximum | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Debt, measurement input 0.123      
Level 3 | Consolidated SLST | Collateral prepayment rate | Valuation Technique, Discounted Cash Flow | Weighted Average | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Debt, measurement input 0.061      
Level 3 | Consolidated SLST | Collateral prepayment rate | Valuation Technique, Discounted Cash Flow | Minimum | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Debt, measurement input 0.028      
Level 3 | Consolidated SLST | Collateral prepayment rate | Valuation Technique, Discounted Cash Flow | Maximum | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Debt, measurement input 0.073      
Level 3 | Consolidated SLST | Collateral default rate | Valuation Technique, Discounted Cash Flow | Weighted Average | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Debt, measurement input 0.011      
Level 3 | Consolidated SLST | Collateral default rate | Valuation Technique, Discounted Cash Flow | Minimum | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Debt, measurement input 0      
Level 3 | Consolidated SLST | Collateral default rate | Valuation Technique, Discounted Cash Flow | Maximum | Consolidated SLST | VIE, Primary Beneficiary        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]        
Debt, measurement input 0.196