Quarterly report pursuant to Section 13 or 15(d)

Fair Value - Summary of HECM Buyouts (Detail)

v3.21.2
Fair Value - Summary of HECM Buyouts (Detail) - HECM Buyouts [Member]
9 Months Ended 12 Months Ended
Sep. 30, 2021
Dec. 31, 2020
Minimum [Member] | Loss frequency [Member]    
Fair Value HECM Buyouts Securitized Nonperforming Mortgage Loans Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loss frequency 25.00% 25.00%
Minimum [Member] | Loss severity [Member]    
Fair Value HECM Buyouts Securitized Nonperforming Mortgage Loans Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loss severity 4.10% 5.10%
Maximum [Member] | Loss frequency [Member]    
Fair Value HECM Buyouts Securitized Nonperforming Mortgage Loans Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loss frequency 100.00% 100.00%
Maximum [Member] | Loss severity [Member]    
Fair Value HECM Buyouts Securitized Nonperforming Mortgage Loans Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loss severity 11.80% 13.30%
Weighted Average [Member] | Conditional repayment rate [Member]    
Fair Value HECM Buyouts Securitized Nonperforming Mortgage Loans Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Conditional repayment rate 41.20% 42.90%
Weighted Average [Member] | Loss frequency [Member]    
Fair Value HECM Buyouts Securitized Nonperforming Mortgage Loans Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loss frequency 59.90% 54.80%
Weighted Average [Member] | Loss severity [Member]    
Fair Value HECM Buyouts Securitized Nonperforming Mortgage Loans Held For Investment Subject To Nonrecourse Debt Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Loss severity 6.10% 7.50%
Discount rate 3.60% 4.10%