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Significant Accounting Policies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended			12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Summary of Significant Accounting Policies [Abstract]
Percentage of fixed maturity portfolio utilizing market approach				95.00%
Investment yields assumed in premium deficiency assessment	4.00%	3.60%	2.90%
Deferred policy acquisition costs amortized to expense				$ 430.8	$ 429.5	$ 428.6

X

- Definition

This element represents the investment yields assumed in the premium deficiency assessment, which are based on the entity's actual average investment yield before tax as of the calculation date.

+ References

No definition available.

+ Details

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X

- Definition

This element represents the percentage of our fixed maturity portfolio utilizing a market approach, primarily using matrix pricing models prepared by external pricing services.

+ References

No definition available.

+ Details

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- Details

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- Definition

Amount of deferred policy acquisition costs charged to expense in the period, generally in proportion to related revenue earned, estimated gross profits, or over the customer relationship or some other period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6967983&loc=d3e11264-158415



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 7

-Article 7



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 20

-Section 45

-Paragraph 2

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6480726&loc=d3e6691-158385



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 16

-Article 12



Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 30

-Section 35

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=6481450&loc=d3e10157-158409



Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 60

-Paragraph 60

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.7(a))

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913



Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 95-1

-Paragraph 19, 20, 21, 22, 23

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 18

-Article 12



Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 97

-Paragraph 22, 23, 24, 25, 26

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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