CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues:
Earned insurance premiums	$ 274.7	$ 321.8	$ 556.8	$ 611.1
Net investment income	19.2	13.2	37.1	25.8
Net realized and unrealized investment gains (losses)	28.1	(15.0)	57.6	10.0
Other revenue	36.2	48.7	76.0	76.1
Total revenues	358.2	368.7	727.5	723.0
Expenses:
Loss and loss adjustment expenses	182.0	196.2	343.1	364.1
Insurance and Reinsurance Acquisition Expenses	50.1	57.8	102.8	110.8
Other Underwriting Expense	51.0	53.0	106.4	109.0
General and administrative expenses	73.1	63.4	160.2	134.3
Interest expense	4.1	3.4	8.6	6.9
Total expenses	360.3	373.8	721.1	725.1
Pre-tax (loss) income from continuing operations	(2.1)	(5.1)	6.4	(2.1)
Income tax benefit (expense)	6.0	2.2	15.7	(2.4)
Net income (loss) from continuing operations	3.9	(2.9)	22.1	(4.5)
Net gain on sale of discontinued operations	366.6	(0.1)	366.6	7.9
Net (loss) income from discontinued operations, net of tax	(8.0)	(0.4)	(6.9)	62.9
Income (loss) before equity in earnings of unconsolidated affiliates	362.5	(3.4)	381.8	66.3
Equity in earnings of unconsolidated affiliates, net of tax	0.0	6.8	0.0	14.1
Net income	362.5	3.4	381.8	80.4
Net (income) loss attributable to non-controlling interests	(21.4)	0.9	(27.7)	8.2
Net income attributable to White Mountains’s common shareholders	341.1	4.3	354.1	88.6
Other comprehensive (loss) income, net of tax:
Change in equity in net unrealized gains from investments in Symetra common shares, net of tax	0.0	(61.8)	0.0	(32.9)
Change in foreign currency translation, pension liability and other, net of tax	0.0	0.2	0.1	0.2
Comprehensive income (loss)	449.2	(13.3)	499.5	12.3
Other comprehensive (loss) income attributable to non-controlling interests	0.0	0.0	0.0	0.0
Comprehensive income (loss) attributable to White Mountains’s common shareholders	$ 449.2	$ (13.3)	$ 499.5	$ 12.3
Basic income per share
Continuing operations	$ (3.44)	$ 0.80	$ (1.07)	$ 2.96
Discontinued operations	70.37	(0.08)	67.64	11.84
Total consolidated operations	66.93	0.72	66.57	14.80
Diluted income per share
Continuing operations	(3.43)	0.80	(1.06)	2.96
Discontinued operations	70.22	(0.08)	67.56	11.84
Total consolidated operations	66.79	0.72	66.50	14.80
Dividends declared per White Mountains’s common share	$ 0.00	$ 0.00	$ 1.00	$ 1.00
Sirius Group
Revenues:
Net realized and unrealized investment gains (losses)	$ 0.4	$ 2.4	$ 3.7	$ 2.7
Expenses:
Net gain on sale of discontinued operations			366.6
Other comprehensive (loss) income, net of tax:
Accumulated Other Comprehensive Income Loss Net Of Tax Other Period Increase Decrease	(5.2)	44.0	32.0	(43.6)
Sale of Sirius Group [Member]
Other comprehensive (loss) income, net of tax:
Accumulated Other Comprehensive Income Loss Net Of Tax Other Period Increase Decrease	$ 113.3	$ 0.0	$ 113.3	$ 0.0