Investments - Commercial Mortgage Loan Securitization and Variable Interest Entities (Details) $ in Thousands	12 Months Ended
Dec. 31, 2016 USD ($)
Investments, Debt and Equity Securities [Abstract]
Certain mortgage loans on real estate transferred into trust	$ 48,761
Cash proceeds from securitization	51,379
Realized gain from securitization	2,415
Securities purchased at fair value	3,400
Maximum loss exposure	3,245
Maximum loss exposure in recorded carrying value	$ 29,674

Maximum potential amount of future undiscounted payments that could be required under the credit derivative, before reduction for potential recoveries under recourse or collateralization provisions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4K
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5708775-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Credit Derivative
-URI http://asc.fasb.org/extlink&oid=6854095

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- Definition

A gain (loss) realized on a transfer, accounted for as a sale, of all or a portion of financial assets in which the transferor surrenders control and receives consideration other than a beneficial interest in the assets transferred. Reflects the amount of sales proceeds in excess of, or deficient from, the sum of the carrying amounts of transferred financial assets plus transaction costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.7,9)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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- References

No definition available.

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- Definition

The fair value, as of the date of each statement of financial position presented, of finance receivables which are owned but transferred to serve as collateral for the payment of the related debt obligation, and that are reclassified and separately reported in the statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

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- Definition

The cash inflow from the securitization of loans held for investment. Securitization is the structured process whereby interests in loans and other receivables are packaged, underwritten, and sold in the form of asset-backed securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3574-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

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-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3521-108585

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- Definition

Fair value portion of interest continued to be held by a transferor after transferring financial assets to a third party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 10
-Section 15
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68074228&loc=d3e94415-111705

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The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5728-111685

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-Publisher FASB
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-Subparagraph (c)
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