Investments - Securities Posted as Collateral (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Securities Posted as Collateral
Commercial mortgage loans and home equity mortgages posted as collateral associated with obligation under funding agreements with the Federal Home Loan Bank of Des Moines	$ 2,872.0	$ 2,562.8
Fixed maturity securities posted as collateral for a reinsurance arrangement, derivative credit support annex (collateral) agreements, Futures Commission Merchant agreements, a lending arrangement and an obligation under funding agreements with Federal Home Loan Bank of Des Moines	2,384.7	2,233.2
Securities posted as collateral eligible to be sold or repledged	$ 150.1	$ 272.8

Carrying amount as of the balance sheet date of fixed maturity securities that have been pledged as collateral for a reinsurance arrangement, derivative credit support annex agreements, Futures Commission Merchant agreements, a lending arrangement and an obligation under funding agreements with Federal Home Loan Bank of Des Moines.

No definition available.

+ Details

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Balance Type:	debit
Period Type:	instant

- References

No definition available.

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- Definition

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 where counterparty has the right to re-pledge such.

+ References

+ Details

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- Definition

Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

+ 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

Reference 2: 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=84173941&loc=d3e5086-111524

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