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Reserve for Claims and Claim Expenses (Cumulative Number of Claims Reported) (Details) - Excess of Loss Reinsurance Contracts | Dec. 31, 2017 claim
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Accident Year 2008 | Property |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 1,355
Accident Year 2008 | Casualty and Specialty |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 1,395
Accident Year 2009 | Property |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 743
Accident Year 2009 | Casualty and Specialty |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 1,112
Accident Year 2010 | Property |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 784
Accident Year 2010 | Casualty and Specialty |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 1,052
Accident Year 2011 | Property |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 1,184
Accident Year 2011 | Casualty and Specialty |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 1,367
Accident Year 2012 | Property |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 679
Accident Year 2012 | Casualty and Specialty |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 1,354
Accident Year 2013 | Property |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 628
Accident Year 2013 | Casualty and Specialty |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 1,409
Accident Year 2014 | Property |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 549
Accident Year 2014 | Casualty and Specialty |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 1,771
Accident Year 2015 | Property |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 591
Accident Year 2015 | Casualty and Specialty |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 1,569
Accident Year 2016 | Property |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 818
Accident Year 2016 | Casualty and Specialty |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 1,114
Accident Year 2017 | Property |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 1,173
Accident Year 2017 | Casualty and Specialty |
Claims Development [Line Items] |
Cumulative number of reported claims (in claims) | 313

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Number of reported claims for short-duration insurance contracts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4D -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=65670685&loc=SL65671317-158438 + Details
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