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Derivative Financial Instruments (Balance Sheet Information) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative fair value	$ 574	$ 234
Investments-trading [Member] | TBAs and Other Forward Agency MBS[Member]
Derivatives, Fair Value [Line Items]
Derivative fair value	5,277	1,063
Investments-trading [Member] | Other Extended Settlement Trades [Member]
Derivatives, Fair Value [Line Items]
Derivative fair value		55
Other Investment At Fair Value [Member] | Foreign currency forward contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative fair value	3	(26)
Trading securities sold, not yet purchased [Member] | TBAs and Other Forward Agency MBS[Member]
Derivatives, Fair Value [Line Items]
Derivative fair value	$ (4,706)	(607)
Trading securities sold, not yet purchased [Member] | Other Extended Settlement Trades [Member]
Derivatives, Fair Value [Line Items]
Derivative fair value		$ (251)

X

- Definition

Fair value of the assets less the liabilities of a derivative or group of derivatives.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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X

- Definition

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+ References

No definition available.

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