Investing Activities Schedule of Available-for-sale Securities Reconciliation (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Marketable Securities, Fixed Maturities [Abstract]
Proceeds from sales	$ 90.0	$ 160.0	$ 68.5
Proceeds from maturities/repayments	286.1	285.3	180.0
Gross investment gains from sales, prepayments and maturities	11.3	22.8	2.4
Gross investment losses from sales and maturities	$ (0.4)	$ (0.7)	$ (0.8)

The cash inflow associated with the maturity (principal being due), prepayment and call (request of early payment) of other investments not otherwise defined in the taxonomy.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3521-108585

Reference 2: 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=31042434&loc=d3e3574-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

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