Segment Information (Tables)

6 Months Ended

Jun. 30, 2013

Segment Reporting [Abstract]

Financial information for White Mountains' segments

Significant intercompany transactions among White Mountains’ segments have been eliminated herein. Financial information for White Mountains’ segments follows:

							HG Global/BAM
Millions	OneBeacon			Sirius Group			HG			BAM			Other Operations			Total
Three Months Ended June 30, 2013
Earned insurance and reinsurance premiums	$	280.8		$	216.6		$	.1		$	—		$	—		$	497.5
Net investment income	11.4			11.4			.2			1.1			4.6			28.7
Net investment income - surplus note income	—			—			10.0			(10.0		)	—			—
Net realized and unrealized investment    (losses) gains	(25.5		)	6.7			(2.0		)	(9.4		)	(7.1		)	(37.3		)
Other revenue	.6			(16.0		)	—			—			15.8			.4
Total revenues	267.3			218.7			8.3			(18.3		)	13.3			489.3
Losses and loss adjustment expenses	157.0			117.6			—			—			—			274.6
Insurance and reinsurance acquisition expenses	52.5			23.2			—			.4			—			76.1
Other underwriting expenses	54.6			29.8			—			.1			—			84.5
General and administrative expenses	2.9			6.0			.5			7.9			22.9			40.2
Interest expense on debt	3.3			6.5			—			—			.5			10.3
Total expenses	270.3			183.1			.5			8.4			23.4			485.7
Pre-tax (loss) income	$	(3.0	)	$	35.6		$	7.8		$	(26.7	)	$	(10.1	)	$	3.6

						HG Global/BAM
Millions	OneBeacon		Sirius Group			HG			BAM			Other Operations		Total
Six Months Ended June 30, 2013
Earned insurance and reinsurance premiums	$	567.3	$	425.5		$	.1		$	—		$	—	$	992.9
Net investment income	20.8		24.5			.5			2.2			9.2		57.2
Net investment income - surplus note income	—		—			20.1			(20.1		)	—		—
Net realized and unrealized investment    gains (losses)	2.9		19.8			(2.2		)	(10.5		)	27.9		37.9
Other revenue	24.6		(5.5		)	—			.1			9.5		28.7
Total revenues	615.6		464.3			18.5			(28.3		)	46.6		1,116.7
Losses and loss adjustment expenses	305.9		213.0			—			—			—		518.9
Insurance and reinsurance acquisition expenses	107.3		66.5			—			.5			—		174.3
Other underwriting expenses	103.9		59.5			—			.2			—		163.6
General and administrative expenses	6.9		15.5			.8			16.1			44.7		84.0
Interest expense on debt	6.5		13.1			—			—			.9		20.5
Total expenses	530.5		367.6			.8			16.8			45.6		961.3
Pre-tax income (loss)	$	85.1	$	96.7		$	17.7		$	(45.1	)	$	1.0	$	155.4

Millions	OneBeacon			Sirius Group			Other Operations			Total
Three Months Ended June 30, 2012
Earned insurance and reinsurance premiums	$	280.3		$	230.2		$	—		$	510.5
Net investment income	14.0			17.1			9.3			40.4
Net realized and unrealized investment (losses) gains	(11.9		)	18.1			(14.3		)	(8.1		)
Other revenue	.2			(17.6		)	16.9			(.5		)
Total revenues	282.6			247.8			11.9			542.3
Losses and loss adjustment expenses	151.4			112.5			—			263.9
Insurance and reinsurance acquisition expenses	60.9			48.6			—			109.5
Other underwriting expenses	51.3			27.0			—			78.3
General and administrative expenses	2.6			6.2			33.3			42.1
Interest expense on debt	4.0			6.6			.3			10.9
Total expenses	270.2			200.9			33.6			504.7
Pre-tax income (loss)	$	12.4		$	46.9		$	(21.7	)	$	37.6

Millions	OneBeacon		Sirius Group		Other Operations			Total
Six Months Ended June 30, 2012
Earned insurance and reinsurance premiums	$	552.1	$	456.4	$	—		$	1,008.5
Net investment income	28.7		34.2		19.3			82.2
Net realized and unrealized investment gains	17.9		31.8		.8			50.5
Other revenue	.3		.7		29.7			30.7
Total revenues	599.0		523.1		49.8			1,171.9
Losses and loss adjustment expenses	287.8		225.9		—			513.7
Insurance and reinsurance acquisition expenses	119.0		99.6		—			218.6
Other underwriting expenses	98.8		53.0		—			151.8
General and administrative expenses	5.3		25.1		57.2			87.6
Interest expense on debt	8.1		13.1		.6			21.8
Total expenses	519.0		416.7		57.8			993.5
Pre-tax income (loss)	$	80.0	$	106.4	$	(8.0	)	$	178.4