Residential Mortgage Loans Held-For-Securitization - Summary of Residential Mortgage Loans Held-for-Investment (Detail) - Residential Mortgage Backed Securities $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2020 USD ($) loan	Dec. 31, 2019 USD ($) loan
Portfolio Characteristics:
Number of loans \| loan	279	300
Current principal balance \| $	$ 137,911	$ 148,908
Average loan balance \| $	$ 494	$ 496
Net weighted average coupon rate	5.41%	5.40%
Weighted average FICO score	742	744
Performance:
Current \| $	$ 135,385	$ 146,999
Total \| $	$ 137,911	$ 148,908
LTV
Portfolio Characteristics:
Weighted average LTV (loan-to-value)	70.00%	70.00%
DTI
Portfolio Characteristics:
Weighted average DTI (debt-to-income)	39.00%	38.00%
30 days delinquent
Performance:
Delinquent \| $	$ 2,115	$ 1,909
60 days delinquent
Performance:
Delinquent \| $	$ 411
12-months bank statements
Portfolio Characteristics:
Number of loans \| loan	15	17
24-months bank statements
Portfolio Characteristics:
Number of loans \| loan	51	56
Alt documentation
Portfolio Characteristics:
Number of loans \| loan	87	97
Full documentation
Portfolio Characteristics:
Number of loans \| loan	13	15
Written Verification of Employment
Portfolio Characteristics:
Number of loans \| loan	113	115

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Current performance.

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Financing receivable recorded investment.

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Portfolio characteristics.

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Percentage of weighted average debt to income.

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Weighted average FICO score.

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Percentage of weighted average loan to value.

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Interest rate of mortgage loan within investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

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Financing receivables that are current.

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Recorded Investment in financing receivables that are past due at the balance sheet date.

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Amount of investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

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-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

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