Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 7

-Section 03

-Paragraph 12

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

-Topic 210

-SubTopic 10

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

-Section S99

-Name Accounting Standards Codification

-Publisher FASB

-Paragraph 1

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

-Publisher FASB

-Name Statement of Financial Accounting Concepts (CON)

-Number 6

-Paragraph 25

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 18

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.18)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Discontinued Operations (Details) (USD $) In Millions, unless otherwise specified							3 Months Ended		9 Months Ended		1 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Dec. 31, 2009	Sep. 30, 2011 Sirius Group.	Sep. 30, 2010 Sirius Group.	Sep. 30, 2011 Sirius Group.	Sep. 30, 2010 Sirius Group.	Aug. 31, 2011 AutoOne OneBeacon Segment count	Sep. 30, 2011 Businesses classified as discontinued operations	Dec. 31, 2010 Businesses classified as discontinued operations
Discontinued Operations
Investment income and realized and unrealized investment gains and losses previously included in the Esurance segment excluded from net income (loss) from discontinued operations							$ 0.9	$ 0.9	$ (2.4)	$ 3.7
Number of insurance entities (AOIC and AOSIC) sold under the agreement to sell the AutoOne business to Interboro (in counts)											2
Assets held for sale
Fixed maturity investments, at fair value	5,287.7		5,786.1									585.0	593.8
Short-term investments, at amortized cost (which approximates fair value)	772.8		975.3									224.9	131.0
Common equity securities, at fair value	669.8		667.0										43.0
Convertible fixed maturity investments, at fair value	140.5		143.0										17.2
Other long-term investments	328.8		372.1										4.0
Total investments	7,199.6		7,943.5									809.9	789.0
Cash	557.7		395.0									235.7	39.8
Reinsurance recoverable on paid and unpaid losses												34.6	34.4
Insurance premiums receivable	644.8		532.5									128.2	102.9
Deferred acquisition costs	202.9		176.1									42.8	34.7
Deferred tax asset	431.7		431.9									88.2	67.8
Other assets	760.2		730.0									60.1	54.2
Total assets	14,581.7		14,534.1									1,399.5	1,122.8
Liabilities held for sale
Loss and loss adjustment expense reserves	5,882.0	5,642.4	5,736.8	5,970.4	6,198.1	6,379.2						514.9	450.4
Unearned insurance premiums	976.4		938.7									258.3	201.6
Accrued incentive compensation	169.9		157.4									31.5	19.1
Other liabilities	1,310.6		1,167.7									104.7	80.4
Total liabilities	10,562.6		10,273.3									909.4	751.5
Net assets held for sale												$ 490.1	$ 371.3