Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section 45

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- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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- Definition

Amount borrowed under the credit facility as of the balance sheet date.

+ References

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-Name Regulation S-X (SX)

-Number 210

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- Definition

Fair value of the amount outstanding under the credit facility.

+ References

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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-Name Regulation S-X (SX)

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

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Debt and Standby Letter of Credit Facilities (Debt Outstanding) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2007	Oct. 10, 2014
Debt Instrument
Debt	$ 746.6us-gaap_LongTermDebt	$ 676.4us-gaap_LongTermDebt
SIG Senior Notes
Debt Instrument
Debt instrument at face value			400.0
Other Debt [Member]
Debt Instrument
Debt	4.8	2.1
OneBeacon \| 2012 OBH Senior Notes
Debt Instrument
Debt instrument at face value	275.0	275.0
Unamortized original issue discount	(0.3)	(0.3)
Debt	274.7	274.7
Sirius Group \| SIG Senior Notes
Debt Instrument
Debt instrument at face value	400.0	400.0
Unamortized original issue discount	(0.3)	(0.4)
Debt	399.7	399.6
White Mountains \| WTM Bank Facility
Debt Instrument
Debt	0	0
Tranzact [Member] \| Tranzact Bank Facility [Member]
Debt Instrument
Line of Credit Facility, Fair Value of Amount Outstanding	67.4	0		70.0
Line of Credit Facility, Amount Outstanding	68.7	0
Unamortized Debt Issuance Expense	$ (1.3)	$ 0