Collateral Finance and Securitization Notes Collateral Finance and Securitization Notes (List of Collateral Finance and Securitization Notes) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Collateralized Financings	$ 783,938	$ 840,700
Debt Issuance Cost	(20,405)	(22,218)
Timerberlake Financial [Member]
Collateralized Financings	411,951	451,880
Reinsurance Group Of America Barbados [Member]
Collateralized Financings	159,100	148,820
Chesterfield Financial Holdings LLC [Member]
Collateralized Financings	217,800	246,300
Debt Issuance Cost	(5,400)
Secured Debt [Member]
Debt Issuance Cost	$ (4,913)	$ (6,300)

The value of the collateral (typically cash) that the entity receives in a financing transaction in exchange for securities lent. This item represents a liability in the financial statements of the lender of the securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(m)(1)(i)(A)(ii))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 25
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64840732&loc=d3e113275-111724

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant