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Discontinued Operations - Foreign Currency Swap and LOCs (Details) ¥ in Billions	Sep. 30, 2015 USD ($)	Apr. 28, 2015 USD ($)	Apr. 28, 2015 JPY (¥)	Nov. 25, 2014 USD ($)
Currency Swap [Member] \| Sirius Group
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Derivative, fair value, net	$ (2,300,000)
Currency Swap [Member] \| Sirius Group \| Euro Member Countries, Euro
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Notional amount \| ¥			¥ 0.1
Currency Swap [Member] \| Sirius Group \| Sweden, Kronor
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Notional amount		$ 50,000,000
Letter of Credit [Member] \| Sirius International [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
number of Credit Lines				2
Line of Credit Facility, Fair Value of Amount Outstanding				$ 200,000,000
Nordea Bank Finland
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total commitment under revolving credit facility				125,000,000.0
Lloyds Bank plc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total commitment under revolving credit facility				75,000,000.0
Unsecured Debt [Member] \| Nordea Bank Finland
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total commitment under revolving credit facility				100,000,000.0
Unsecured Debt [Member] \| Lloyds Bank plc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total commitment under revolving credit facility				$ 25,000,000.0