SCHEDULE VI SUPPLEMENTAL INFORMATION FOR PROPERTY AND CASUALTY INSURANCE UNDERWRITERS (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
SUPPLEMENTAL INFORMATION FOR PROPERTY AND CASUALTY INSURANCE UNDERWRITERS
Rate at which reserves are discounted (as a percent)	3.50%		3.50%		5.00%
OneBeacon
SUPPLEMENTAL INFORMATION FOR PROPERTY AND CASUALTY INSURANCE UNDERWRITERS
Deferred acquisition costs(4)	$ 103.7	[1]	$ 123.9	[1]	$ 123.5	[1]
Reserves for Unpaid Claims and Claims Adjustment Expenses	1,054.3	[1]	1,000.0	[1]	3,358.6	[1]
Discount, if any, deducted in Column C	3.0	[1],[2]	4.6	[1],[2]	271.6	[1],[2]
Unearned Premiums	544.9	[1]	573.8	[1]	528.0	[1]
Earned Premiums	1,120.4	[1]	1,132.0	[1]	1,012.2	[1]
Net investment income	41.1	[1]	53.6	[1]	71.4	[1]
Claims and ClaimsAdjustment ExpensesIncurred Related to, Current Year	622.1	[1]	657.4	[1]	578.1	[1]
Claims and ClaimsAdjustment ExpensesIncurred Related to, Prior Year	0	[1]	(7.4)	[1]	(29.8)	[1]
Amortization of deferred policy acquisition(4) costs	208.9	[1],[3]	249.4	[1],[3]	221.2	[1],[3]
Paid Claims and Claims Adjustment Expenses	540.7	[1]	565.1	[1]	523.2	[1]
Premiums written	1,088.6	[1]	1,179.2	[1]	1,062.7	[1]
Sirius Group
SUPPLEMENTAL INFORMATION FOR PROPERTY AND CASUALTY INSURANCE UNDERWRITERS
Deferred acquisition costs(4)	69.3		71.4		63.5
Reserves for Unpaid Claims and Claims Adjustment Expenses	2,025.0		2,168.9		2,343.7
Discount, if any, deducted in Column C	1.7	[4]	2.4	[4]	12.8	[4]
Unearned Premiums	343.3		350.2		319.0
Earned Premiums	866.4		931.6		912.3
Net investment income	30.3		65.0		89.9
Claims and ClaimsAdjustment ExpensesIncurred Related to, Current Year	466.8		578.4		672.9
Claims and ClaimsAdjustment ExpensesIncurred Related to, Prior Year	(48.4)		(34.5)		(46.9)
Amortization of deferred policy acquisition(4) costs	166.5	[3]	180.8	[3]	181.0	[3]
Paid Claims and Claims Adjustment Expenses	628.1		741.2		642.0
Premiums written	$ 876.6		$ 947.7		$ 915.7

[1] The amounts shown excludes balances reclassified to held for sale in the consolidated balance sheets related to the Runoff Transaction as of December 31, 2013 and 2012 and to AutoOne as of December 31, 2011. See Note 21 - “Discontinued Operations”.

[2] The amounts shown represent OneBeacon’s discount on its long-term workers compensation loss and LAE reserves, as such liabilities constitute unpaid but settled claims under which the payment pattern and ultimate costs are fixed and determinable on an individual basis. OneBeacon discounts these reserves using a discount rate which is determined based on the facts and circumstances applicable at the time the claims are settled (3.5%, 3.5% and 5.0% at December 31, 2013, 2012 and 2011). Also the amounts shown include unamortized fair value adjustments to reserves for unpaid claims and claims adjustment expenses made in purchase accounting as a result of White Mountains’ purchase of OneBeacon for the years ended December 31, 2013, 2012 and 2011.

[3] ) In 2012, the Company adopted ASU 2010-26, Accounting for Costs Associated with Acquiring or Renewing Insurance Contracts (ASC 944). See Note 1 - “Summary of Significant Accounting Policies”.

[4] The amount shown represents unamortized fair value adjustments to reserves for unpaid claims and claims adjustment expenses made in purchase accounting as a result of White Mountains’ purchase of Sirius International during 2004.