Loans Receivable, Net - Overall Statistics for Loans Receivable Portfolio (Detail) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2022 USD ($) SecurityLoan loan	Dec. 31, 2021 USD ($) loan SecurityLoan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans \| SecurityLoan	205	188
Principal balance	$ 24,576,601	$ 22,156,437
Net book value	$ 24,278,702	$ 21,878,338
Weighted-average maximum maturity (years)	3 years 3 months 18 days	3 years 4 months 24 days
Percentage of Portfolio	100.00%	100.00%
Number of loans accounted for under cost-recovery method \| loan	1	1
Unfunded Loan Commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded loan commitments	$ 4,126,886	$ 4,180,128
Floating Rate Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Portfolio		99.50%
Fixed Rate Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Portfolio		0.50%
Prepayment Restrictions Including Yield Maintenance Lock Out Provisions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Portfolio	61.00%	56.00%
Without Prepayment Restrictions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Portfolio	39.00%	44.00%
LIBOR
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted-average cash coupon (percentage)	3.30%	3.19%
Weighted-average all-in yield (percentage)	3.67%	3.52%

Financing Receivable, Commitment to Lend

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- Definition

Financing Receivable, Number of Loans

+ References

No definition available.

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- Definition

Financing Receivable, Number of Loans Accounted For Under Cost-Recovery Method

+ References

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- Definition

Financing Receivable, Percentage Of Loan Portfolio

+ References

No definition available.

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- Definition

Mortgage loan on real estate final maturity term.

+ References

No definition available.

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- Definition

Weighted Average Cash Coupon Rate

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amortized cost excluding accrued interest, after allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

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- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, fee, and loan in process, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 20
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=6378536&loc=d3e10095-111533

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
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-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

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- Definition

Yield on the receivable, on which interest has been imputed, as calculated from its issuance value or purchase price. The calculated effective interest rate considers factors such as the issued face value or price paid for the receivable, the time period between payments, and the time until maturity [full receipt] of the receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

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