CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues:
Earned insurance premiums	$ 2.2	$ 3.3	$ 5.2	$ 6.8
Net investment income	14.7	6.1	27.5	8.6
Net realized and unrealized investment gains	33.7	3.4	70.0	16.3
Advertising and commission revenues	33.2	29.2	71.7	63.0
Other revenue	1.6	7.2	4.5	13.3
Total revenues	85.4	49.2	178.9	108.0
Expenses:
Loss and loss adjustment expenses	0.0	2.3	1.1	4.6
Insurance acquisition expenses	0.9	1.4	2.2	3.1
Other underwriting expenses	0.1	0.1	0.2	0.2
Cost of sales	26.8	24.4	55.6	52.9
General and administrative expenses	57.5	45.2	117.9	99.9
Interest expense	0.5	0.9	0.9	2.1
Total expenses	85.8	74.3	177.9	162.8
Pre-tax (loss) income from continuing operations	(0.4)	(25.1)	1.0	(54.8)
Income tax benefit	1.0	4.0	1.3	5.6
Net income (loss) from continuing operations	0.6	(21.1)	2.3	(49.2)
Net (loss) gain on sale of discontinued operations, net of tax	(0.6)	366.6	(1.6)	366.6
Net income from discontinued operations, net of tax	3.4	17.0	35.7	64.4
Net income	3.4	362.5	36.4	381.8
Net loss (income) attributable to non-controlling interests	12.1	(21.4)	13.4	(27.7)
Net income attributable to White Mountains’s common shareholders	15.5	341.1	49.8	354.1
Comprehensive income, net of tax:
Change in foreign currency translation	0.6	(0.2)	1.4	(0.1)
Comprehensive income	16.3	449.2	51.5	499.5
Other comprehensive income attributable to non-controlling interests	(0.1)	0.0	(0.1)	0.0
Comprehensive income attributable to White Mountains’s common shareholders	$ 16.2	$ 449.2	$ 51.4	$ 499.5
Basic income (loss) per share
Continuing operations (in usd per share)	$ 2.78	$ (8.34)	$ 3.42	$ (14.47)
Discontinued operations (in usd per share)	0.61	75.27	7.47	81.04
Total consolidated operations (in usd per share)	3.39	66.93	10.89	66.57
Diluted income (loss) per share
Continuing operations (in usd per share)	2.78	(8.32)	3.42	(14.46)
Discontinued operations (in usd per share)	0.61	75.11	7.47	80.96
Total consolidated operations (in usd per share)	3.39	66.79	10.89	66.50
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		$ 0.4		$ 3.7
Expenses:
Net (loss) gain on sale of discontinued operations, net of tax	$ (0.6)
Discontinued Operations
Revenues:
Earned insurance premiums	277.4	309.1	$ 539.2	790.1
Net investment income	14.5	14.3	26.7	40.9
Net realized and unrealized investment gains	12.3	32.0	27.3	39.8
Total revenues	306.3	407.9	598.7	977.9
Expenses:
Loss and loss adjustment expenses	188.6	220.9	339.2	493.4
Insurance acquisition expenses	48.4	59.3	93.7	158.7
Other underwriting expenses	59.6	55.1	111.3	137.1
General and administrative expenses	8.8	52.9	13.8	118.3
Interest expense	3.3	5.8	6.6	17.1
Total expenses	308.7	394.0	564.6	924.6
Net income from discontinued operations, net of tax	3.4	17.0	35.7	64.4
Net income attributable to White Mountains’s common shareholders	2.8	378.6	33.7	426.1
Comprehensive income, net of tax:
Change in foreign currency translation	0.2	108.3	0.3	145.5
Comprehensive income	$ 3.0	$ 491.9	$ 34.4	$ 576.5
Basic income (loss) per share
Total consolidated operations (in usd per share)	$ 0.61	$ 75.27	$ 7.47	$ 81.04
Diluted income (loss) per share
Total consolidated operations (in usd per share)	$ 0.61	$ 75.11	$ 7.47	$ 80.96
Discontinued Operations | Sirius Group
Revenues:
Earned insurance premiums	$ 0.0	$ 37.7		$ 240.1
Net investment income	0.0	2.2		14.4
Net realized and unrealized investment gains	0.0	7.3		(1.5)
Total revenues	0.0	51.9		253.6
Expenses:
Loss and loss adjustment expenses	0.0	41.2		154.9
Insurance acquisition expenses	0.0	10.6		59.0
Other underwriting expenses	0.0	4.2		30.9
General and administrative expenses	0.0	2.3		10.4
Interest expense	0.0	1.3		7.9
Total expenses	0.0	59.6		263.1
Net (loss) gain on sale of discontinued operations, net of tax	(0.6)
Net income from discontinued operations, net of tax	0.0	(5.5)		(6.4)
Comprehensive income, net of tax:
Change in foreign currency translation		(5.2)		32.0
Comprehensive income	$ (0.6)	$ 469.2	$ (0.6)	$ 505.5