Loans Held for Investment - Collateral Characteristics (Detail) $ in Thousands	Dec. 31, 2019 USD ($) loan	Dec. 31, 2018 USD ($) loan
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Number of loans	139,194	140,345
Loans Held for Investment at Fair Value \| Seasoned Subprime Residential Mortgage Loans
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Number of loans	139,194	140,345
Weighted average maturity (years)	19 years 3 months 18 days	18 years 7 months 6 days
Weighted average loan to value	87.40%	87.50%
Weighted average FICO	627	629
Weighted average loan balance (in thousands) \| $	$ 95	$ 89
Weighted average percentage owner occupied	88.00%	90.10%
Weighted average percentage single family residence	84.40%	86.30%
Loans Held for Investment at Fair Value \| CA \| Seasoned Subprime Residential Mortgage Loans
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Weighted average geographic concentration of top five states	11.60%	9.00%
Loans Held for Investment at Fair Value \| FL \| Seasoned Subprime Residential Mortgage Loans
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Weighted average geographic concentration of top five states	7.40%	7.30%
Loans Held for Investment at Fair Value \| OH \| Seasoned Subprime Residential Mortgage Loans
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Weighted average geographic concentration of top five states	5.30%	5.90%
Loans Held for Investment at Fair Value \| NY \| Seasoned Subprime Residential Mortgage Loans
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Weighted average geographic concentration of top five states	6.90%	5.70%
Loans Held for Investment at Fair Value \| PA \| Seasoned Subprime Residential Mortgage Loans
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Weighted average geographic concentration of top five states	5.30%	5.60%

Indicates the number of mortgages under each classification.

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- Definition

Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]

+ References

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- Definition

The weighted average maturity period of underlying mortgages, which is based on their current face amounts.

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No definition available.

+ Details

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- Definition

As of the balance sheet date, the weighted average of underlying mortgages at amortized cost to their fair values determined using defined pricing methodologies.

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No definition available.

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- Definition

As of the balance sheet date, the weighted average credit score of underlying mortgages based on their FICO ratings.

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No definition available.

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- Definition

As of the balance sheet date, the percentage of unpaid principal amount of underlying mortgages originated in a specified territory.

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No definition available.

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- Definition

As of the balance sheet date, the weighted average of unpaid principal amounts of underlying mortgages.

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No definition available.

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- Definition

As of the balance sheet date, the weighted average of underlying mortgages that are owner occupied.

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No definition available.

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- Definition

As of the balance sheet date, the weighted average of underlying mortgages that are single family residences.

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No definition available.

+ Details

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