Borrowings (Amounts at Risk) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2023	Dec. 31, 2022
Nomura Holdings Inc.
Borrowings [Line Items]
Repurchase Agreement Counterparty, Amount at Risk	$ 207,771	$ 208,812
Repurchase Agreement Counterparty, Weighted Average Maturity of Agreements	100 days	13 days
Nomura Holdings Inc. \| Fair Value, Concentration of Risk, Maximum Amount of Loss
Borrowings [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	15.50%	17.10%
Royal Bank of Canada [Member]
Borrowings [Line Items]
Repurchase Agreement Counterparty, Amount at Risk		$ 135,233
Repurchase Agreement Counterparty, Weighted Average Maturity of Agreements		100 days
Royal Bank of Canada [Member] \| Fair Value, Concentration of Risk, Maximum Amount of Loss
Borrowings [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance		11.10%

[Line Items] for Borrowings [Table]

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
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-URI https://asc.fasb.org//1943274/2147482861/275-10-50-18

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-Topic 275
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-Section 50
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482861/275-10-50-20

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- Definition

The amount at risk under repurchase agreements is defined as the excess of carrying amount (or market value, if higher than the carrying amount or if there is no carrying amount) of the securities or other assets sold under agreement to repurchase, including accrued interest plus any cash or other assets on deposit to secure the repurchase obligation, over the amount of the repurchase liability (adjusted for accrued interest).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(m)(1)(iii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

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- Definition

Weighted average maturity (weighted by amount of the agreement) of repurchase agreements with the counterparty, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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