CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues:
Net investment income	$ 21.0	$ 11.8	$ 37.0	$ 31.5
Net realized and unrealized investment gains (losses)			280.8	(43.2)
Total revenues	129.0	122.3	562.6	164.4
Expenses:
Broker commission expense		6.6		6.6
Amortization of other intangible assets	4.2	0.0	10.8
Total expenses	113.2	134.7	265.1	242.8
Pre-tax income (loss) from continuing operations	15.8	(12.4)	297.5	(78.4)
Income tax benefit (expense)	0.1	(2.5)	(10.1)	(3.2)
Net income (loss) from continuing operations	15.9	(14.9)	287.4	(81.6)
Net gain from sale of discontinued operations, net of tax	0.0	0.0	0.7	0.1
Net income (loss)	15.9	(14.9)	288.1	(81.5)
Net loss attributable to non-controlling interests	4.6	18.4	16.8	37.0
Net income (loss) attributable to White Mountains’s common shareholders	20.5	3.5	304.9	(44.5)
HG Global-BAM
Revenues:
Earned insurance premiums	4.3	3.4	8.5	6.4
Net investment income	5.4	4.0	10.7	7.7
Net realized and unrealized investment gains (losses)	11.5	(2.4)	23.3	(10.3)
Commission revenues	0.0	0.0	0.0	0.0
Other revenue	0.4	0.4	1.0	0.6
Total revenues	21.6	5.4	43.5	4.4
Expenses:
Insurance acquisition expenses	1.4	1.3	2.7	2.7
Other underwriting expenses	0.1	0.1	0.2	0.2
General and administrative expenses	12.3	13.4	26.6	25.2
Broker commission expense	0.0		0.0
Change in fair value of contingent consideration earnout liabilities	0.0		0.0
Cost of sales	0.0	0.0	0.0	0.0
Amortization of other intangible assets	0.0	0.0	0.0	0.0
Interest expense	0.0	0.0	0.0	0.0
Total expenses	13.8	14.8	29.5	28.1
Pre-tax income (loss) from continuing operations	7.8	(9.4)	14.0	(23.7)
NSM Holding Co LLC
Revenues:
Earned insurance premiums	0.0		0.0
Net investment income	0.0		0.0
Net realized and unrealized investment gains (losses)	0.0		0.0
Commission revenues	54.9	22.6	98.2	22.6
Other revenue	11.2	0.9	17.2	0.9
Total revenues	66.1	23.5	115.4	23.5
Expenses:
Insurance acquisition expenses	0.0		0.0
Other underwriting expenses	0.0		0.0
General and administrative expenses	32.7	12.1	57.8	12.1
Broker commission expense	18.2	6.6	33.9	6.6
Change in fair value of contingent consideration earnout liabilities	6.3	0.0	7.6	0.0
Cost of sales	0.0		0.0
Amortization of other intangible assets	4.1	0.0	9.1	0.0
Interest expense	4.1	1.6	7.8	1.6
Total expenses	65.4	20.3	116.2	20.3
Pre-tax income (loss) from continuing operations	0.7		(0.8)	3.2
Kudu Investment Management, LLC
Revenues:
Earned insurance premiums	0.0
Net investment income	4.0	0.0	4.0	0.0
Net realized and unrealized investment gains (losses)	0.4	0.0	0.4	0.0
Commission revenues	0.0
Other revenue	0.0		0.0
Total revenues	4.4	0.0	4.4	0.0
Expenses:
Insurance acquisition expenses	0.0
Other underwriting expenses	0.0
General and administrative expenses	2.2	0.0	2.2	0.0
Broker commission expense	0.0
Change in fair value of contingent consideration earnout liabilities	0.0
Cost of sales	0.0
Amortization of other intangible assets	0.0
Total expenses	2.2	0.0	2.2	0.0
Pre-tax income (loss) from continuing operations	2.2		2.2
MediaAlpha
Revenues:
Earned insurance premiums		0.0	0.0	0.0
Net investment income		0.0	0.0	0.0
Net realized and unrealized investment gains (losses)		0.0	0.0	0.0
Commission revenues	0.0	71.8	48.8	141.9
Other revenue	0.0	0.0	0.0	1.6
Total revenues	0.0	71.8	48.8	143.5
Expenses:
Insurance acquisition expenses		0.0	0.0	0.0
Other underwriting expenses		0.0	0.0	0.0
General and administrative expenses	0.0	4.6	12.5	15.8
Broker commission expense			0.0
Change in fair value of contingent consideration earnout liabilities			0.0
Cost of sales	0.0	59.9	40.6	117.3
Amortization of other intangible assets	0.0	2.5	1.6	5.4
Interest expense	0.0	0.3	0.2	0.7
Total expenses	0.0	67.3	54.9	139.2
Pre-tax income (loss) from continuing operations		4.5	(6.1)	4.3
Other Segment
Revenues:
Earned insurance premiums	0.0	0.0	0.0	0.0
Net investment income	11.6	7.8	22.3	23.8
Net realized and unrealized investment gains (losses)	23.3	12.9	142.4	(32.9)
Realized and unrealized gains from the MediaAlpha Transaction				0.0
Commission revenues	1.3	1.0	2.6	1.9
Other revenue	0.7	(0.1)	1.0	0.2
Total revenues	36.9	21.6	350.5	(7.0)
Expenses:
Insurance acquisition expenses	0.0		0.0
Other underwriting expenses	0.0		0.0
General and administrative expenses	30.1	31.0	59.5	53.0
Broker commission expense	0.0		0.0
Change in fair value of contingent consideration earnout liabilities	0.0		0.0
Cost of sales	1.6	1.1	2.7	1.8
Amortization of other intangible assets	0.1	0.1	0.1	0.1
Interest expense	0.0	0.1	0.0	0.3
Total expenses	31.8	32.3	62.3	55.2
Pre-tax income (loss) from continuing operations	5.1	(10.7)	288.2	(62.2)
Discontinued Operations
Expenses:
Net income (loss) attributable to White Mountains’s common shareholders	$ 20.5	$ 3.5	304.9	(44.5)
Swedish Tax Authority | Discontinued Operations | Sirius Group
Expenses:
Net gain from sale of discontinued operations, net of tax				$ 0.1
MediaAlpha | HG Global-BAM
Revenues:
Realized and unrealized gains from the MediaAlpha Transaction			0.0
MediaAlpha | NSM Holding Co LLC
Revenues:
Realized and unrealized gains from the MediaAlpha Transaction			0.0
MediaAlpha | Other Segment
Revenues:
Realized and unrealized gains from the MediaAlpha Transaction			$ 182.2