Loans Receivable, Net - Overall Statistics for Loans Receivable Portfolio (Detail) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2022 USD ($) loan SecurityLoan	Dec. 31, 2021 USD ($) SecurityLoan loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans \| SecurityLoan	203	188
Principal balance	$ 23,873,563	$ 22,156,437
Net book value	$ 23,586,769	$ 21,878,338
Weighted-average maximum maturity (years)	3 years 6 months	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	$ 4,545,691	$ 4,180,128
Floating Rate Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Portfolio	99.60%	99.50%
Fixed Rate Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Portfolio	0.40%	0.50%
Prepayment Restrictions Including Yield Maintenance Lock Out Provisions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Portfolio	59.00%	56.00%
Without Prepayment Restrictions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Portfolio	41.00%	44.00%
LIBOR
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted-average cash coupon (percentage)	3.22%	3.19%
Weighted-average all-in yield (percentage)	3.57%	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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- Definition

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

Amount, before allowance for credit loss, fee, and loan in process, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount excluding accrued interest, after allowance for credit loss, of financing receivable.

+ 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 http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

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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 http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

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