CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Assets
Common equity securities, at fair value	$ 650.0	$ 538.4
Other long-term investments	2,150.2	1,998.2
Total investments	6,477.6	6,388.7
Goodwill and other intangible assets	720.3	370.6
Total assets	9,925.6	8,385.9
Liabilities
Debt	562.5	564.6
Total liabilities	4,794.6	3,824.3
White Mountains’s common shareholders’ equity
White Mountains’s common shares at $1 par value per share—authorized 50,000,000 shares; issued and outstanding 2,568,148 and 2,560,452 shares	2.6	2.6
Paid-in surplus	563.8	548.7
Retained earnings	3,919.0	3,690.8
Accumulated other comprehensive income (loss), after-tax:
Net unrealized gains (losses) from foreign currency translation	(1.7)	(1.6)
Total White Mountains’s common shareholders’ equity	4,483.7	4,240.5
Noncontrolling interests	647.3	321.1
Total equity	5,131.0	4,561.6
Total liabilities and equity	9,925.6	8,385.9
Other Operations
Assets
Fixed maturity investments, at fair value	293.7	230.2
Common equity securities, at fair value	224.6	137.8
Short-term investments, at fair value	262.1	425.2
Other long-term investments	588.4	661.0
Investment in MediaAlpha, at fair value	201.6	254.9
Total investments	1,570.4	1,709.1
Cash	38.6	23.8
Insurance premiums receivable	15.3	0.0
Goodwill and other intangible assets	64.8	69.8
Other assets	65.1	73.2
Total assets	1,754.2	1,875.9
Liabilities
Loss and loss adjustment expense reserves	12.1	0.0
Unearned insurance premiums	29.0	0.0
Debt	22.0	28.4
Accrued incentive compensation	79.3	87.7
Other liabilities	38.9	25.0
Total liabilities	181.3	141.1
Accumulated other comprehensive income (loss), after-tax:
Total White Mountains’s common shareholders’ equity	1,563.8	1,725.4
Noncontrolling interests	9.1	9.4
P&C Insurance and Reinsurance (Ark/WM Outrigger)
Liabilities
Loss and loss adjustment expense reserves	2,127.5	1,605.1
P&C Insurance and Reinsurance (Ark/WM Outrigger) | Operating Segments
Assets
Fixed maturity investments, at fair value	1,565.1	866.8
Common equity securities, at fair value	425.4	400.6
Short-term investments, at fair value	601.4	962.8
Other long-term investments	547.8	440.9
Total investments	3,139.7	2,671.1
Cash	141.2	90.5
Reinsurance recoverables	589.0	442.0
Insurance premiums receivable	768.6	612.2
Deferred acquisition costs	165.2	145.3
Goodwill and other intangible assets	292.5	292.5
Other assets	202.8	125.0
Total assets	5,299.0	4,378.6
Liabilities
Loss and loss adjustment expense reserves	2,127.5	1,605.1
Unearned insurance premiums	853.3	743.6
Debt	154.5	185.5
Reinsurance payable	149.5	81.1
Contingent consideration	155.3	94.0
Other liabilities	224.7	166.8
Total liabilities	3,664.8	2,876.1
Accumulated other comprehensive income (loss), after-tax:
Total White Mountains’s common shareholders’ equity	1,223.8	1,165.6
Noncontrolling interests	410.4	336.9
Financial Guarantee (HG Global) | Operating Segments
Assets
Fixed maturity investments, at fair value	612.1	1,012.3
Short-term investments, at fair value	55.5	70.6
Total investments	667.6	1,082.9
Cash	11.5	6.7
BAM Surplus Notes, at fair value	381.7	0.0
Insurance premiums receivable	4.4	5.5
Deferred acquisition costs	86.6	40.1
Other assets	27.6	36.8
Total assets	1,179.4	1,172.0
Liabilities
Unearned insurance premiums	297.3	325.8
Debt	147.4	146.9
Other liabilities	19.4	59.0
Total liabilities	464.1	531.7
Accumulated other comprehensive income (loss), after-tax:
Total White Mountains’s common shareholders’ equity	728.7	779.3
Noncontrolling interests	(13.4)	(139.0)
Asset Management (Kudu) | Operating Segments
Assets
Short-term investments, at fair value	27.9	29.3
Other long-term investments	1,014.0	896.3
Total investments	1,041.9	925.6
Cash	0.6	1.4
Accrued investment income	18.0	17.6
Goodwill and other intangible assets	8.0	8.3
Other assets	39.9	6.5
Total assets	1,108.4	959.4
Liabilities
Debt	238.6	203.8
Other liabilities	78.1	71.6
Total liabilities	316.7	275.4
Accumulated other comprehensive income (loss), after-tax:
Total White Mountains’s common shareholders’ equity	664.1	570.2
Noncontrolling interests	127.6	113.8
P&C Insurance Distribution (Bamboo) | Operating Segments
Assets
Fixed maturity investments, at fair value	40.7	0.0
Short-term investments, at fair value	17.3	0.0
Total investments	58.0	0.0
Cash	74.5	0.0
Premiums, commissions and fees receivable	70.0	0.0
Goodwill and other intangible assets	355.0	0.0
Other assets	27.1	0.0
Total assets	584.6	0.0
Liabilities
Loss and loss adjustment expense reserves	17.8	0.0
Unearned insurance premiums	31.5	0.0
Premiums and commissions payable	88.1	0.0
Other liabilities	30.3	0.0
Total liabilities	167.7	0.0
Accumulated other comprehensive income (loss), after-tax:
Total White Mountains’s common shareholders’ equity	303.3	0.0
Noncontrolling interests	$ 113.6	$ 0.0