Investments (Aging Of Commercial Mortgage Loans By Property Type) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 Days Past Due	$ 2.8	$ 10.4
60 Days Past Due	2.7	3.6
Greater Than 90 Days Past Due	5.9	11.6
Financing Receivable, Recorded Investment, Past Due, Total	11.4	25.6
Allowance Related to Past Due	(2.3)	(3.3)
Current	5,312.0	5,382.8
Total commercial mortgage loans	5,321.1	5,405.1
Retail [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 Days Past Due	0.2	2.8
60 Days Past Due	2.0	0.3
Greater Than 90 Days Past Due	4.8	6.1
Financing Receivable, Recorded Investment, Past Due, Total	7.0	9.2
Allowance Related to Past Due	(2.1)	(1.5)
Current	2,622.2	2,621.5
Total commercial mortgage loans	2,627.1	2,629.2
Office [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 Days Past Due	1.9	1.3
60 Days Past Due	0	0
Greater Than 90 Days Past Due	0.8	3.7
Financing Receivable, Recorded Investment, Past Due, Total	2.7	5.0
Allowance Related to Past Due	0	(0.9)
Current	1,010.7	978.3
Total commercial mortgage loans	1,013.4	982.4
Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 Days Past Due	0.5	0
60 Days Past Due	0	3.3
Greater Than 90 Days Past Due	0.3	1.8
Financing Receivable, Recorded Investment, Past Due, Total	0.8	5.1
Allowance Related to Past Due	(0.2)	(0.9)
Current	1,000.9	1,004.5
Total commercial mortgage loans	1,001.5	1,008.7
Hotels And Motels [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 Days Past Due	0	6.3
60 Days Past Due	0	0
Greater Than 90 Days Past Due	0	0
Financing Receivable, Recorded Investment, Past Due, Total	0	6.3
Allowance Related to Past Due	0	0
Current	165.7	270.0
Total commercial mortgage loans	165.7	276.3
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 Days Past Due	0	0
60 Days Past Due	0	0
Greater Than 90 Days Past Due	0	0
Financing Receivable, Recorded Investment, Past Due, Total	0	0
Allowance Related to Past Due	0	0
Current	213.6	218.6
Total commercial mortgage loans	213.6	218.6
Apartment And Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 Days Past Due	0.2	0
60 Days Past Due	0.7	0
Greater Than 90 Days Past Due	0	0
Financing Receivable, Recorded Investment, Past Due, Total	0.9	0
Allowance Related to Past Due	0	0
Current	298.9	289.9
Total commercial mortgage loans	$ 299.8	$ 289.9

Amount of allowance for commercial mortgage loans past due.

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- Definition

Financing receivables that are less than 60 days past due but more than 29 days past due.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7A

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524

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Financing receivables that are less than 90 days past due but more than 59 days past due.

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Financing receivables that are current.

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Financing receivables that are equal to or greater than 90 days past due.

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Recorded Investment in financing receivables that are past due at the balance sheet date.

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- Definition

The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

+ 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(c))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph c

-Article 7

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