Quarterly report pursuant to Section 13 or 15(d)

Mortgage Loans Held for Sale, at Fair Value - Schedule of Mortgage Loans Held For Sale that were Greater Than 90 Days Past Due And On Non-Accrual Status (Detail)

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Mortgage Loans Held for Sale, at Fair Value - Schedule of Mortgage Loans Held For Sale that were Greater Than 90 Days Past Due And On Non-Accrual Status (Detail) - USD ($)
$ in Thousands
Sep. 30, 2021
Dec. 31, 2020
Mortgage Loans Held For Sale That Were Greater Than 90 Days Past Due And OnNonAccrualStatus [Line Items]    
Mortgage loans held for sale, Aggregate Unpaid Principal Balance $ 7,046 $ 18,553
Mortgage loans held for sale, Total Difference (838) (2,874)
Residential Mortgage Loans [Member]    
Mortgage Loans Held For Sale That Were Greater Than 90 Days Past Due And OnNonAccrualStatus [Line Items]    
Mortgage loans held for sale, Aggregate Unpaid Principal Balance 3,905 13,236
Commercial Mortgage Loans [Member]    
Mortgage Loans Held For Sale That Were Greater Than 90 Days Past Due And OnNonAccrualStatus [Line Items]    
Mortgage loans held for sale, Aggregate Unpaid Principal Balance 3,141 5,317
Loans 90 Days Or More Past Due And On Non Accrual Status [Member]    
Mortgage Loans Held For Sale That Were Greater Than 90 Days Past Due And OnNonAccrualStatus [Line Items]    
Mortgage loans held for sale, Fair Value 6,208 15,679
Loans 90 Days Or More Past Due And On Non Accrual Status [Member] | Residential Mortgage Loans [Member]    
Mortgage Loans Held For Sale That Were Greater Than 90 Days Past Due And OnNonAccrualStatus [Line Items]    
Mortgage loans held for sale, Fair Value 3,256 10,628
Loans 90 Days Or More Past Due And On Non Accrual Status [Member] | Commercial Mortgage Loans [Member]    
Mortgage Loans Held For Sale That Were Greater Than 90 Days Past Due And OnNonAccrualStatus [Line Items]    
Mortgage loans held for sale, Fair Value $ 2,952 $ 5,051