Quarterly report pursuant to Section 13 or 15(d)

Fair Value - Summary of Non-Agency Reverse Mortgage Securitized (Detail)

v3.22.1
Fair Value - Summary of Non-Agency Reverse Mortgage Securitized (Detail) - Non Agency Reverse Mortgage Securitized [Member]
3 Months Ended 12 Months Ended
Mar. 31, 2022
Dec. 31, 2021
Minimum [Member] | Loan to value [Member]    
Fair Value Non Agency Reverse Mortgage Loan Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loan to value 0.10% 0.10%
Minimum [Member] | Home price appreciation [Member]    
Fair Value Non Agency Reverse Mortgage Loan Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Home price appreciation 4.30% 4.60%
Maximum [Member] | Loan to value [Member]    
Fair Value Non Agency Reverse Mortgage Loan Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loan to value 69.00% 64.70%
Maximum [Member] | Home price appreciation [Member]    
Fair Value Non Agency Reverse Mortgage Loan Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Home price appreciation 15.80% 14.00%
Weighted Average [Member] | Weighted average remaining life in years [Member]    
Fair Value Non Agency Reverse Mortgage Loan Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Weighted-average remaining life in years 7 days 19 hours 7 days 12 hours
Weighted Average [Member] | Loan to value [Member]    
Fair Value Non Agency Reverse Mortgage Loan Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loan to value 43.10% 43.40%
Weighted Average [Member] | Conditional repayment rate [Member]    
Fair Value Non Agency Reverse Mortgage Loan Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Conditional repayment rate 17.50% 18.60%
Weighted Average [Member] | Loss severity [Member]    
Fair Value Non Agency Reverse Mortgage Loan Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loss severity 10.00% 10.00%
Weighted Average [Member] | Home price appreciation [Member]    
Fair Value Non Agency Reverse Mortgage Loan Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Home price appreciation 4.70% 4.70%
Weighted Average [Member] | Discount rate [Member]    
Fair Value Non Agency Reverse Mortgage Loan Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Discount rate 4.90% 3.60%