Commitments and Contingencies - Restricted Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Other fixed maturities-state deposits	$ 13.4	$ 13.5
Securities pledged	767.9	249.2
Total restricted assets	781.3	262.7
Fixed maturities
Loss Contingencies [Line Items]
Fair value of securities delivered as collateral	219.7	70.3
Securities pledged
Loss Contingencies [Line Items]
Fair value of loaned securities	548.2	178.9
Fair value of securities delivered as collateral	$ 219.7	$ 70.3

The fair value of available-for-sale securities that serve as collateral for borrowings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5086-111524

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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.

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For an unclassified balance sheet, this item represents investments in debt securities having predetermined or determinable maturity dates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(a))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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Investments which are not defined as or included in marketable (debt, equity, or other) securities whose use is restricted in whole or in part, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

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Fair value of the securities pledged as collateral against securities loaned.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226013-175313

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Fair value of financial instrument held by the entity for its own account (proprietary securities) for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729

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-Publisher FASB
-Name Accounting Standards Codification
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