CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Net income (loss)	$ 148.8	$ 15.7
Charges (credits) to reconcile net income to net cash (used for) provided from operations:
Net realized and unrealized investment gains (losses)	(50.5)	(33.6)
Net income from discontinued operations	(0.1)	(1.0)
Undistributed equity in earnings from unconsolidated affiliates, net of tax	(16.7)	(14.6)
Deferred income tax expense (benefit)	31.9	(24.6)
Other operating items:
Net change in loss and loss adjustment expense reserves	(365.5)	(148.7)
Net change in reinsurance recoverable on paid and unpaid losses	126.9	182.2
Net change in unearned insurance and reinsurance premiums	224.9	77.2
Net change in funds held by ceding companies	(1.9)	(7.6)
Net change in variable annuity benefit guarantee liabilities	(106.7)	(18.9)
Net change in variable annuity derivative instruments	(40.1)	78.5
Net change in deferred acquisition costs	(13.9)	(14.9)
Net change in ceded unearned premiums	(49.9)	48.0
Net change in funds held under reinsurance treaties	5.0	(47.7)
Net change in insurance and reinsurance premiums receivable	(263.2)	(127.0)
Net change in ceded reinsurance payable	43.2	(65.3)
Net change in other assets and liabilities, net	54.0	(42.6)
Net cash used for operations - continuing operations	(273.8)	(144.9)
Net cash (used for) provided from operations - discontinued operations	(2.0)	9.3
Net cash used for operations	(275.8)	(135.6)
Cash flows from investing activities:
Net change in short-term investments	171.7	162.7
Sales of fixed maturity and convertible fixed maturity investments	3,239.6	2,110.9
Maturities, calls and paydowns of fixed maturity and convertible fixed maturity investments	296.6	825.7
Sales of common equity securities	58.8	84.9
Distributions and redemptions of other long-term investments	20.0	77.9
Purchases of other long-term investments	(13.9)	(22.7)
Contributions to discontinued operations	0	(58.7)
Purchases of common equity securities	(225.5)	(91.4)
Purchases of fixed maturity and convertible fixed maturity investments	(2,491.7)	(2,647.2)
Net change in unsettled investment purchases and sales	(61.6)	38.5
Net acquisitions of property and equipment	(0.8)	(4.1)
Net cash provided from investing activities - continuing operations	993.2	476.5
Net cash used for investing activities - discontinued operations	0	7.9
Net cash provided from investing activities	993.2	484.4
Cash flows from financing activities:
Repayment of debt	0	(161.6)
Cash dividends paid to the Company's common shareholders	(6.6)	(8.0)
Cash dividends paid to OneBeacon Ltd.'s noncontrolling common shareholders	(9.9)	(33.0)
Cash dividends paid on SIG Preference Shares	(9.4)	(9.4)
Common shares repurchased	(491.0)	(93.3)
Proceeds from issuances of common shares	0	1.0
Net cash used for financing activities - continuing operations	(516.9)	(304.3)
Net cash provided from financing activities - discontinued operations	0	0
Net cash used for financing activities	(516.9)	(304.3)
Effect of exchange rate changes on cash	(0.8)	2.4
Net change in cash during the period	199.7	46.9
Net change in cash from discontinued operations	(2.0)	(17.2)
Cash reclassified from assets held for sale (net of cash sold of $3.5)	2.0	0
Cash balances at beginning of period (excludes restricted cash balances of $453.5 and $286.7 and AutoOne cash of $0 and $4.7)	251.9	103.6
Cash balances at end of period (excludes restricted cash balances of $ 360.1 and $345.9 and AutoOne cash of $0 and $4.5)	451.6	133.3
Supplemental cash flows information:
Interest paid	(20.9)	(23.7)
Net income tax payments to national governments	$ (13.4)	$ (25.3)