CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (USD $) In Millions	Total	White Mountains' Common Shareholders' Equity	Common shareholders' equity	Common shares and paid-in surplus	Retained earnings	Accum. other comprehensive income (loss), after-tax	Non-controlling interest
Balances at Dec. 31, 2009			$ 3,657.4	$ 1,445.0	$ 2,215.9	$ (3.5)	$ 684.1
Increase (Decrease) in Stockholders' Equity
Cumulative effect adjustment - ASU 2009-17			(0.4)		(0.4)		(22.8)
Cumulative effect adjustment - ASU 2009-17 (ASU 2009-17)		(0.4)			(0.4)		(22.8)
Net (loss) income	(25.0)		(37.1)		(37.1)		12.1
Other comprehensive income, after-tax			2.3			2.3
Dividends declared on common shares	(8.8)		(8.8)		(8.8)
Dividends to noncontrolling interests							(19.1)
Repurchases and retirements of common shares			(118.3)	(57.4)	(60.9)
Issuances of common shares			0.8	0.8
Net distributions to noncontrolling interests							(7.6)
Amortization of restricted share and option awards			17.7	17.7			0.1
Balances at Jun. 30, 2010			3,513.6	1,406.1	2,108.7	(1.2)	646.8
Balances at Dec. 31, 2010	4,260.8		3,653.0	1,359.0	2,175.6	118.4	607.8
Increase (Decrease) in Stockholders' Equity
Net (loss) income	15.7		(16.5)		(16.5)		32.2
Other comprehensive income, after-tax			78.6			78.6
Dividends declared on common shares	(8.0)		(8.0)		(8.0)
Dividends to noncontrolling interests							(42.4)
Repurchases and retirements of common shares			(93.2)	(44.1)	(49.1)
Issuances of common shares			0.9	0.9
Net distributions to noncontrolling interests							(2.6)
Amortization of restricted share and option awards			5.7	5.7			0.3
Balances at Jun. 30, 2011	$ 4,215.8		$ 3,620.5	$ 1,321.5	$ 2,102.0	$ 197.0	$ 595.3