Quarterly report pursuant to Section 13 or 15(d)

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

v3.22.1
Fair Value - Summary of Non-Agency Reverse Mortgage Loans (Detail) - Non Agency Reverse Mortgage Loans [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 Loans Classified As Reverse Mortgage Loans Held For Investment Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loan to value 2.90% 0.20%
Minimum [Member] | Home price appreciation [Member]    
Fair Value Non Agency Reverse Mortgage Loans Classified As Reverse Mortgage Loans Held For Investment 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 Loans Classified As Reverse Mortgage Loans Held For Investment Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loan to value 69.10% 68.70%
Maximum [Member] | Home price appreciation [Member]    
Fair Value Non Agency Reverse Mortgage Loans Classified As Reverse Mortgage Loans Held For Investment 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 Loans Classified As Reverse Mortgage Loans Held For Investment Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Weighted-average remaining life in years 9 years 10 months 24 days 9 years 2 months 12 days
Weighted Average [Member] | Loan to value [Member]    
Fair Value Non Agency Reverse Mortgage Loans Classified As Reverse Mortgage Loans Held For Investment Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loan to value 47.20% 47.80%
Weighted Average [Member] | Conditional repayment rate [Member]    
Fair Value Non Agency Reverse Mortgage Loans Classified As Reverse Mortgage Loans Held For Investment Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Conditional repayment rate 13.60% 14.80%
Weighted Average [Member] | Loss severity [Member]    
Fair Value Non Agency Reverse Mortgage Loans Classified As Reverse Mortgage Loans Held For Investment 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 Loans Classified As Reverse Mortgage Loans Held For Investment Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Home price appreciation 4.30% 4.40%
Weighted Average [Member] | Discount rate [Member]    
Fair Value Non Agency Reverse Mortgage Loans Classified As Reverse Mortgage Loans Held For Investment Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Discount rate 4.90% 3.60%