Investments (Trading Account Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Investment [Line Items]
Trading Securities, Cost	$ 154,608	$ 5,618
Trading Securities, Fair Value	149,871	5,653
Equity securities, available-for-sale
Investment [Line Items]
Equity Securities, Cost	7,551	5,618
Equity Securities, Fair Value	10,358	5,653
Fixed maturities
Investment [Line Items]
Fixed Maturities, Cost	147,057	0
Fixed Maturities, Fair Value	$ 139,513	$ 0

Line items represent reporting 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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 12
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.4)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-URI http://asc.fasb.org/extlink&oid=6526789

Reference 4: http://www.xbrl.org/2003/role/presentationRef
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