Nature of Operations and Significant Accounting Policies (Details 2) (USD $) In Millions	3 Months Ended	6 Months Ended
Mar. 31, 2010 Retained earnings (deficit) Effects of implementation of accounting change related to variable interest entities, net	Mar. 31, 2010 Accumulated other comprehensive income (loss) Effects of implementation of accounting change related to variable interest entities, net	Dec. 31, 2010 Retained earnings (deficit) Effects of electing fair value option for fixed maturities upon implementation of accounting change related to embedded credit derivatives, net	Dec. 31, 2010 Accumulated other comprehensive income (loss) Effects of electing fair value option for fixed maturities upon implementation of accounting change related to embedded credit derivatives, net	Jul. 31, 2010 Effects of electing fair value option for fixed maturities upon implementation of accounting change related to embedded credit derivatives, net
Recent Accounting Pronouncements Disclosures
Cumulative effect of adoption of new accounting principle, increase (decrease) in equity account	$ (10.7)	$ 10.7	$ (25.4)	$ 25.4
Fair value of fixed maturities reclassified from available-for-sale to trading					$ 75.3

Effect of a change in accounting principle on a financial statement line item and any per share amounts affected for the prior period presented. The cumulative effect of the change on retained earnings or net assets in the statement of financial position, as of the beginning of the earliest period presented.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 154

-Paragraph 17

-Subparagraph b(2), b(3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 250

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6801783&loc=d3e22580-107794

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 250

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=6801783&loc=d3e22499-107794

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Period Type:	duration