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Derivatives (Interest rate cap) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 9 Months Ended |  |  | 1 Months Ended | 3 Months Ended | 9 Months Ended |  |
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Sep. 30, 2014 Interest Rate Cap Rating | Sep. 30, 2014 Interest Rate Cap Rating | Jun. 30, 2014 Interest Rate Cap | Dec. 31, 2013 Interest Rate Cap | May 31, 2007 Sirius International Group Ltd Preferred Stock | Sep. 30, 2013 Sirius International Group Ltd Interest Rate Cap | Sep. 30, 2014 Sirius International Group Ltd Interest Rate Cap | Jul. 30, 2013 Sirius International Group Ltd Interest Rate Cap | Sep. 30, 2014 Standard & Poor's, A Rating Barclays Interest Rate Cap | Sep. 30, 2014 Standard & Poor's, AA- Rating Nordea Bank Finland Interest Rate Cap
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative collateral right to reclaim | $ 5.4 | $ 5.4 |  |  |  |  |  |  | $ 3.7 | $ 1.7
Preferred Stock, Dividend Rate, Percentage |  |  |  |  | 7.506% |  |  |  |  |
Term of LIBOR loan |  |  |  |  | 3 months |  |  |  |  |
Derivative, Cap Interest Rate |  |  |  |  |  |  |  | 8.30% |  |
Derivative, Cost of Hedge |  |  |  |  |  |  | 9.9 |  |  |
basis points |  |  |  |  | 3.20% |  | 3.95% |  |  |
Non-cumulative perpetual preference shares issued |  |  |  |  | 250.0 |  |  |  |  |
years of interest rate cap |  |  |  |  |  | 5 years |  |  |  |
Derivative, fair value, net | 5.4 | 5.4 | 6.2 | 11.1 |  |  |  |  |  |
Realized and unrealized gains (losses) | $ (0.8) | $ (5.7) |  |  |  |  |  |  |  |
S and P Credit Ratings | 21 | 21 |  |  |  |  |  |  |  |

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- Definition Fair value of the assets less the liabilities of a derivative or group of derivatives. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 + Details
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- Definition The amount of collateral held against amounts due to counterparties for over the counter derivative instruments against net derivative instrument positions. + References No definition available. + Details
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