Financial Derivatives (Futures) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Mar. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Fair Value		$ (6,950)	$ (10,833)
Short \| Futures
Derivative [Line Items]
Notional Amount		(164,000)	(30,000)
Fair Value		$ (330)	103
Remaining Years to Maturity	3 months 10 days	3 months
Financial Derivatives - Liabilities \| Short \| U.S. Treasury futures
Derivative [Line Items]
Notional Amount		$ (165,600)	(16,000)
Fair Value		$ (300)	148
Remaining Years to Maturity	2 months 23 days	3 months
Financial Derivatives - Liabilities \| Short \| Eurodollar futures
Derivative [Line Items]
Notional Amount		$ 0	(14,000)
Fair Value		$ 0	(45)
Remaining Years to Maturity	4 months 2 days	0 years
Financial Derivatives - Liabilities \| Long \| U.S. Treasury futures
Derivative [Line Items]
Notional Amount		$ 1,900	0
Fair Value		$ (31)	0
Remaining Years to Maturity	0 years	2 months 23 days
Financial Derivatives - Assets \| Short \| U.S. Treasury futures
Derivative [Line Items]
Notional Amount		$ (300)	0
Fair Value		$ 1	$ 0
Remaining Years to Maturity	0 years	2 months 23 days

Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=117331979&loc=d3e41228-113958

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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

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

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- Definition

Period remaining until the derivative contract matures, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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