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Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
Loss Contingencies [Line Items] |  |  |
Rent expense | $ 18.8 | $ 22.8 | $ 28.1
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] |  |  |
Operating lease payments due in 2013 | 14.8 |  |
Operating lease payments due in 2014 | 13.5 |  |
Operating lease payments due in 201 | 11.8 |  |
Operating lease payments due in 2016 and thereafter | 33.3 |  |
Commitments to fund other-long term investments | 124.7 |  |
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] |  |  |
Reserve for probable liability from mandatory shared market mechanisms | 12.9 |  |
Contingencies Related to Sale of Subsidiaries [Abstract] |  |  |
Period for which company has indemnified Allstate for breaches of representations and warranties (in months) | 18 months |  |
Period for which the entity has agreed not to engage in certain competing business activities (in years) | 2 years |  |
Period for which the entity has agreed not to solicit certain employees of transferred subsidiaries (in years) | 3 years |  |
Percentage of positive or negative development in the loss reserves of the Transferred Subsidiaries retained | 90.00% |  |
Number of anniversaries from the closing date for which positive or negative development in the loss reserves of the Transferred Subsidiaries are to be computed | 3 years |  |
Sales of unconsolidated affiliates, net of cash sold and held in escrow | 24.8 | 1,010.6 | 188.3
OB Services |  |  |
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] |  |  |
Cash proceeds received a result of entering into the sale-leaseback transactions | 23.1 |  |
Capital lease obligation | 18.2 | 23.1 |
Capital lease asset | 16.1 | 22.9 |
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] |  |  |
Capital lease payments due in 2013 | 5.3 |  |
Capital lease payments due in 2014 | 5.3 |  |
Capital lease payments due in 2015 | 5.3 |  |
Capital lease payments due in 2016 | $ 1.9 |  |
Furniture and equipment | OB Services |  |  |
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] |  |  |
Capital lease term (in years) | 5 years |  |
Capitalized software | OB Services |  |  |
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] |  |  |
Capital lease term (in years) | 4 years |  |

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