CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Assets
Fixed maturity investments, at fair value	$ 4,785.5	$ 5,030.5
Short-term investments, at amortized cost (which approximates fair value)	834.9	635.9
Common equity securities, at fair value	986.1	1,156.8
Convertible fixed maturity investments, at fair value	48.9	80.5
Other long-term investments	320.9	288.9
Total investments	6,976.3	7,192.6
Cash (restricted: $23.8 and $56.1)	543.5	382.8
Reinsurance recoverable on unpaid losses	430.7	428.1
Reinsurance recoverable on paid losses	27.2	25.4
Insurance and reinsurance premiums receivable	677.8	518.9
Funds held by ceding entities	123.9	106.3
Investments in unconsolidated affiliates	413.5	321.4
Deferred acquisition costs	204.4	174.7
Deferred tax asset	439.1	512.1
Ceded unearned insurance and reinsurance premiums	114.3	92.4
Accrued investment income	32.7	39.3
Accounts receivable on unsettled investment sales	39.0	12.1
Other assets	466.7	458.1
Assets held for sale	1,699.2	1,880.1
Total assets	12,188.3	12,144.3
Liabilities
Loss and loss adjustment expense reserves	3,022.9	3,079.3
Unearned insurance and reinsurance premiums	1,089.5	901.4
Variable annuity benefit guarantee	11.7	52.8
Debt	678.1	676.4
Deferred tax liability	303.0	356.2
Accrued incentive compensation	187.5	218.3
Ceded reinsurance payable	134.0	71.9
Funds held under insurance and reinsurance contracts	132.2	127.1
Accounts payable on unsettled investment purchases	76.0	20.5
Other liabilities	355.4	362.9
Liabilities held for sale	1,699.2	1,880.1
Total liabilities	7,689.5	7,746.9
White Mountains’s common shareholders’ equity
White Mountains’ common shares	6.0	6.2
Paid-in surplus	1,030.9	1,044.9
Retained earnings	2,961.5	2,802.3
Accumulated other comprehensive income (loss), after tax:
Equity in net unrealized gains (losses) from investments in Symetra common shares	19.1	(40.4)
Net unrealized foreign currency translation (losses) gains	(11.9)	88.4
Pension liability and other	4.5	4.1
Total White Mountains’s common shareholders’ equity	4,010.1	3,905.5
Non-controlling interests
Total non-controlling interests	488.7	491.9
Total equity	4,498.8	4,397.4
Total liabilities and equity	12,188.3	12,144.3
OneBeacon
Non-controlling interests
Total non-controlling interests	275.6	273.7
Sirius Group
Non-controlling interests
Total non-controlling interests	250.0	250.0
HG Global
Non-controlling interests
Total non-controlling interests	18.0	16.6
BAM
Non-controlling interests
Total non-controlling interests	(114.3)	(97.6)
Other Noncontrolling Interest [Member]
Non-controlling interests
Total non-controlling interests	$ 59.4	$ 49.2