CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Revenues:
Earned insurance and reinsurance premiums	$ 512.2	$ 478.3	$ 1,011.2	$ 946.1
Net investment income	40.4	45.8	82.2	95.3
Net realized and unrealized investment gains (losses)	(8.1)	42.8	50.5	33.6
Other revenue	(0.5)	(13.3)	30.7	8.2
Total revenues	544.0	553.6	1,174.6	1,083.2
Expenses:
Loss and loss adjustment expenses	265.0	278.5	527.7	636.9
Insurance and reinsurance acquisition expenses	108.7	98.5	217.1	189.2
Other underwriting expenses	79.0	71.4	153.8	144.5
General and administrative expenses	42.1	56.2	87.6	84.2
Interest expense on debt	10.9	12.9	21.8	26.0
Total expenses	505.7	517.5	1,008.0	1,080.8
Pre-tax income (loss) from continuing operations	38.3	36.1	166.6	2.4
Income tax (expense) benefit	(6.6)	(10.0)	(34.6)	(2.3)
Net income (loss) from continuing operations	31.7	26.1	132.0	0.1
Net income from discontinued operations, net of tax	0	(1.5)	0.1	1.0
Income (loss) before equity in earnings of unconsolidated affiliates	31.7	24.6	132.1	1.1
Equity in earnings of unconsolidated affiliates	6.5	7.9	16.7	14.6
Net income (loss)	38.2	32.5	148.8	15.7
Net income attributable to noncontrolling interests	(12.1)	(20.8)	(28.9)	(32.2)
Net income (loss) attributable to White Mountains' common shareholders	26.1	11.7	119.9	(16.5)
Comprehensive income (loss), net of tax:
Change in equity in net unrealized losses from investments in unconsolidated affiliates	28.2	22.1	27.0	22.1
Accumulated Other Comprehensive Income (Loss) Foreign Currency Translation and Other	(29.8)	(5.5)	(6.3)	56.5
Comprehensive income	24.5	28.3	140.6	62.1
Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to White Mountains’ common shareholders	$ 24.5	$ 28.3	$ 140.6	$ 62.1
Basic income (loss) per share
Continuing operations (in dollars per share)	$ 3.92	$ 1.66	$ 17.01	$ (2.19)
Discontinued operations (in dollars per share)	$ 0.00	$ (0.18)	$ 0.02	$ 0.13
Total consolidated operations (in dollars per share)	$ 3.92	$ 1.48	$ 17.03	$ (2.06)
Diluted income (loss) per share
Continuing operations (in dollars per share)	$ 3.92	$ 1.66	$ 17.01	$ (2.19)
Discontinued operations (in dollars per share)	$ 0.00	$ (0.18)	$ 0.02	$ 0.13
Total consolidated operations (in dollars per share)	$ 3.92	$ 1.48	$ 17.03	$ (2.06)
Dividends declared per White Mountains' common share (in dollars per share)	$ 0.00	$ 0.00	$ 1.00	$ 1.00