Fair Value Measurements - Summary of Significant Inputs to Fair Value Measurement (Details) - Fair Value, Inputs, Level 3
Dec. 31, 2021
LoanCost
Dec. 31, 2020
Non-Agency MBS | Annualized Default Rate    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Significant inputs to fair value measurement 0.777 0.120
Non-Agency MBS | Loss-Given-Default    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Significant inputs to fair value measurement 0.158 0.400
Non-Agency MBS | Discount Rate    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Significant inputs to fair value measurement 0.130 0.139
Mortgage Loans of Consolidated VIE | Loss-Given-Default    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Significant inputs to fair value measurement 0.086  
Mortgage Loans of Consolidated VIE | Probability of Default    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Significant inputs to fair value measurement 0.662  
MSR financing receivables | Discount Rate    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Significant inputs to fair value measurement 0.090  
MSR financing receivables | Annualized Prepayment Rate    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Significant inputs to fair value measurement 0.101  
MSR financing receivables | Annual per-loan Cost of Servicing(Current Loans)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Significant inputs to fair value measurement 65.00