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Income Taxes (Tables) | 12 Months Ended
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Dec. 31, 2023
Income Tax Disclosure [Abstract] |
Schedule of total income tax benefit (expense) | December 31, 2023, 2022 and 2021:
|  | Year Ended December 31,
Millions |  | 2023 |  | 2022 |  | 2021
Current income tax (expense) benefit: |  |  |  |  |  |
U.S. federal |  | $ | (12.6) |  |  | $ | (16.9) |  |  | $ | (4.8) |
State |  | (2.2) |  |  | (4.5) |  |  | (2.1) |
Non-U.S. |  | (16.6) |  |  | (7.1) |  |  | (2.8) |
Total current income tax (expense) benefit |  | (31.4) |  |  | (28.5) |  |  | (9.7) |
Deferred income tax (expense) benefit: |  |  |  |  |  |
U.S. federal |  | (13.2) |  |  | (7.3) |  |  | (13.9) |
State |  | (3.8) |  |  | (1.8) |  |  | (7.0) |
Non-U.S. |  | 63.9 |  |  | (3.8) |  |  | (13.8) |
Total deferred income tax (expense) benefit |  | 46.9 |  |  | (12.9) |  |  | (34.7) |
Total income tax (expense) benefit |  | $ | 15.5 |  |  | $ | (41.4) |  |  | $ | (44.4) |
Schedule of U.S. federal statutory income tax rate and actual effective tax rate on pre-tax income | The following table presents a reconciliation of taxes calculated for 2023, 2022 and 2021 using the 21% U.S. federal statutory rate (the tax rate at which the majority of White Mountains’s worldwide operations are taxed) to the income tax (expense) benefit on pre-tax income (loss):
|  | Year Ended December 31,
Millions |  | 2023 |  | 2022 |  | 2021
Tax (expense) benefit at the U.S. statutory rate |  | $ | (118.7) |  |  | $ | 31.4 |  |  | $ | 57.5 |
Differences in taxes resulting from: |  |  |  |  |  |
Non-U.S. earnings, net of foreign taxes |  | 103.7 |  |  | (41.2) |  |  | (78.2) |
Bermuda corporate income tax |  | 68.0 |  |  | — |  |  | — |
Change in valuation allowance |  | (30.2) |  |  | (19.6) |  |  | (2.0) |
State taxes |  | (8.2) |  |  | (2.8) |  |  | (7.3) |
Noncontrolling interest |  | 6.8 |  |  | 3.4 |  |  | 2.1 |
Member’s surplus contributions |  | (5.7) |  |  | (6.2) |  |  | (5.6) |
Withholding tax |  | (4.1) |  |  | (3.1) |  |  | (.3) |
Tax rate changes |  | (.6) |  |  | (.4) |  |  | (10.9) |
Officer compensation |  | (.2) |  |  | (1.0) |  |  | (1.5) |
Tax exempt interest and dividends |  | .2 |  |  | .2 |  |  | .2 |
Other, net |  | 4.5 |  |  | (2.1) |  |  | 1.6 |
Total income tax (expense) benefit on pre-tax income (loss) |  | $ | 15.5 |  |  | $ | (41.4) |  |  | $ | (44.4) |
Schedule of components of deferred income tax assets and liabilities | The following table presents an outline of the significant components of White Mountains’s U.S. federal, state and non-U.S. deferred tax assets and liabilities:
|  | December 31,
Millions |  | 2023 |  | 2022
Deferred tax assets related to: |  |  |  |
U.S. federal and state net operating and capital loss carryforwards |  | $ | 87.6 |  |  | $ | 85.4 |
Non-U.S. net operating loss carryforwards |  | 68.2 |  |  | 36.1 |
Intangible assets |  | 51.5 |  |  | — |
Incentive compensation |  | 25.4 |  |  | 21.4 |
Unearned premiums |  | 18.2 |  |  | — |
Accrued interest |  | 10.1 |  |  | 8.8 |
Loss reserves |  | 8.4 |  |  | — |
Deferred acquisition costs |  | 3.7 |  |  | 8.0 |
Tax credit carryforwards |  | 3.3 |  |  | 1.8 |
Net unrealized investment losses |  | — |  |  | 4.7 |
Other items |  | 1.0 |  |  | 1.3 |
Total gross deferred tax assets |  | 277.4 |  |  | 167.5 |
Less: valuation allowances |  | 116.1 |  |  | 94.3 |
Total net deferred tax assets |  | 161.3 |  |  | 73.2 |
Deferred tax liabilities related to: |  |  |  |
Member’s surplus contributions |  | 82.2 |  |  | 71.3 |
Purchase accounting |  | 43.9 |  |  | 43.9 |
Investment basis difference |  | 40.9 |  |  | 33.9 |
Deferred underwriting |  | 18.3 |  | 9.7 |
Net unrealized investment gains (losses) |  | 15.5 |  |  | — |
Other items |  | 1.2 |  |  | 2.2 |
Total deferred tax liabilities |  | 202.0 |  |  | 161.0 |
Net deferred tax asset (liability) |  | $ | (40.7) |  |  | $ | (87.8) |
Schedule of net operating and capital loss carryforwards | The following table presents net operating loss and capital loss carryforwards as of December 31, 2023, the expiration dates and the deferred tax assets thereon:
|  | December 31, 2023
Millions |  | United States |  | Luxembourg |  |  |  |  |  | United Kingdom |  | Israel |  | Total
2024-2028 |  | $ | — |  |  | $ | — |  |  |  |  |  |  | $ | — |  |  | $ | — |  |  | $ | — |
2029-2033 |  | 90.8 |  |  | — |  |  |  |  |  |  | — |  |  | — |  |  | 90.8 |
2034-2043 |  | 304.1 |  |  | 188.1 |  |  |  |  |  |  | — |  |  | — |  |  | 492.2 |
No expiration date |  | 1.9 |  |  | — |  |  |  |  |  |  | 3.2 |  |  | 89.1 |  |  | 94.2 |
Total |  | $ | 396.8 |  |  | $ | 188.1 |  |  |  |  |  |  | $ | 3.2 |  |  | $ | 89.1 |  |  | $ | 677.2 |
Gross deferred tax asset |  | $ | 87.6 |  |  | $ | 46.9 |  |  |  |  |  |  | $ | .8 |  |  | $ | 20.5 |  |  | $ | 155.8 |
Valuation allowance |  | (87.6) |  |  | (46.9) |  |  |  |  |  |  | (.8) |  |  | (20.5) |  |  | (155.8) |
Net deferred tax asset |  | $ | — |  |  | $ | — |  |  |  |  |  |  | $ | — |  |  | $ | — |  |  | $ | — |

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