CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Assets
Common equity securities, at fair value	$ 637.0	$ 668.4
Other long-term investments	1,895.8	1,488.0
Goodwill and other intangible assets	372.1	392.4
Total assets	8,142.8	7,389.3
Liabilities
Debt	564.7	575.2
Total liabilities	3,978.6	3,454.3
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 2,560,452 and 2,572,156 shares	2.6	2.6
Paid-in surplus	544.9	536.0
Retained earnings	3,404.3	3,211.8
Accumulated other comprehensive income (loss), after-tax:
Net unrealized gains (losses) from foreign currency translation and interest rate swap	(2.7)	(3.5)
Total White Mountains’s common shareholders’ equity	3,949.1	3,746.9
Noncontrolling interests	215.1	188.1
Total equity	4,164.2	3,935.0
Total liabilities and equity	8,142.8	7,389.3
Other Operations
Assets
Fixed maturity investments, at fair value	270.7	238.2
Common equity securities, at fair value	252.1	333.8
Investment in MediaAlpha, at fair value	188.8	168.6
Short-term investments, at fair value	215.5	373.6
Other long-term investments	698.5	418.5
Total investments	1,625.6	1,532.7
Cash	22.9	33.9
Goodwill and other intangible assets	71.2	91.3
Other assets	89.6	155.6
Total assets	1,809.3	1,813.5
Liabilities
Debt	29.6	36.7
Accrued incentive compensation	64.0	86.1
Other liabilities	27.3	34.3
Total liabilities	120.9	157.1
HG Global/BAM | Operating Segments
Assets
Fixed maturity investments, at fair value	932.2	909.9
Short-term investments, at fair value	80.1	65.9
Total investments	1,012.3	975.8
Cash	4.9	18.2
Insurance premiums receivable	5.5	6.6
Deferred acquisition costs	38.5	36.0
Other assets	22.2	21.9
Total assets	1,083.4	1,058.5
Liabilities
Unearned insurance premiums	312.3	298.3
Debt	146.8	146.5
Accrued incentive compensation	19.9	28.0
Other liabilities	40.0	29.0
Total liabilities	519.0	501.8
P&C Insurance and Reinsurance (Ark/WM Outrigger)
Liabilities
Loss and loss adjustment expense reserves	1,571.8	1,296.5
P&C Insurance and Reinsurance (Ark/WM Outrigger) | Operating Segments
Assets
Fixed maturity investments, at fair value	775.0	772.8
Common equity securities, at fair value	384.9	334.6
Short-term investments, at fair value	850.0	484.6
Other long-term investments	416.6	373.6
Total investments	2,426.5	1,965.6
Cash	129.6	101.5
Reinsurance recoverables	538.4	595.3
Insurance premiums receivable	781.6	544.1
Deferred acquisition costs	178.7	127.2
Goodwill and other intangible assets	292.5	292.5
Other assets	66.9	65.2
Total assets	4,414.2	3,691.4
Liabilities
Loss and loss adjustment expense reserves	1,571.8	1,296.5
Unearned insurance premiums	984.6	623.2
Debt	184.6	183.7
Reinsurance payable	146.3	251.1
Contingent consideration	62.1	45.3
Other liabilities	132.0	122.3
Total liabilities	3,081.4	2,522.1
Kudu | Operating Segments
Assets
Short-term investments, at fair value	17.3	0.0
Other long-term investments	780.7	695.9
Total investments	798.0	695.9
Cash	5.4	101.4
Accrued investment income	15.8	12.4
Goodwill and other intangible assets	8.4	8.6
Other assets	8.3	7.6
Total assets	835.9	825.9
Liabilities
Debt	203.7	208.3
Other liabilities	53.6	65.0
Total liabilities	$ 257.3	$ 273.3