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Subsequent Event (Details) (USD $) In Millions, unless otherwise specified | 0 Months Ended | 12 Months Ended
--- | --- | ---
Jan. 02, 2013 | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
Subsequent Event [Line Items] |  |  |  |
Premiums written, net |  | $ 2,126.9 | $ 1,978.4 | $ 2,033.5
Essentia | Subsequent Event |  |  |  |
Subsequent Event [Line Items] |  |  |  |
Gain on sale of disposition, before tax | 23 |  |  |
Gain (loss) on sale of discontinued operation, net of tax | 15 |  |  |
Premiums written, net |  | $ 179.7 | $ 166.6 | $ 153.0
Premiums written, percentage of total |  | 8.00% |  |

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- Definition Premiums written for all insurance and reinsurance contracts, after adding premiums assumed from other insurers and subtracting any amounts ceded to another insurer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 17 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 113 -Paragraph 27 -Subparagraph a, b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (b),(c) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 + Details
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- Details
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- Definition Expected Gain from Sale of Subsidiary after Tax + References No definition available. + Details
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- Definition Premiums Written, Percentage of Total + References No definition available. + Details
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