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v3.24.3

Segment Information - Summary of underwriting income or loss by segment (Details) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2024 USD ($) | Sep. 30, 2023 USD ($) | Sep. 30, 2024 USD ($) segment | Sep. 30, 2023 USD ($) | Dec. 31, 2023 USD ($)
Segment Reporting Information [Line Items] |  |  |  |  |  |
Number of segments | segment |  |  |  | 3 |  |
Gross premiums written |  | $ 5,440 | $ 4,527 | $ 16,755 | $ 14,152 |
Premiums ceded |  | (1,393) | (1,172) | (4,842) | (3,945) |
Net premiums written |  | 4,047 | 3,355 | 11,913 | 10,207 |
Change in unearned premiums |  | (77) | (107) | (956) | (1,111) |
Net premiums earned |  | 3,970 | 3,248 | 10,957 | 9,096 |
Other underwriting income |  | 5 | 5 | 20 | 21 |
Losses and loss adjustment expenses |  | (2,403) | (1,647) | (5,958) | (4,609) |
Acquisition expenses |  | (681) | (575) | (1,921) | (1,669) |
Other operating expenses |  | (353) | (310) | (1,062) | (942) |
Underwriting income (loss) |  | 538 | 721 | 2,036 | 1,897 |
Net investment income |  | 399 | 269 | 1,090 | 710 |
Net realized gains (losses) |  | 169 | (248) | 358 | (354) |
Equity in net income (loss) of investment funds accounted for using the equity method |  | 171 | 59 | 437 | 176 |
Other income (loss) |  | 8 | (4) | 30 | 10 |
Corporate expenses | [1] | (19) | (20) | (88) | (69) |
Transaction costs and other | [1] | (30) | 0 | (55) | (2) |
Amortization of intangible assets |  | (88) | (24) | (136) | (71) |
Interest expense |  | (35) | (34) | (104) | (99) |
Net foreign exchange gains (losses) |  | (63) | 22 | (31) | (1) |
Income (loss) before income taxes and income (loss) from operating affiliates |  | 1,050 | 741 | 3,537 | 2,197 |
Income tax expense (benefit) |  | (98) | (72) | (296) | (203) |
Income (loss) from operating affiliates |  | 36 | 54 | 136 | 115 |
Net income available to Arch |  | 988 | 723 | 3,377 | 2,109 |
Preferred dividends |  | (10) | (10) | (30) | (30) |
Net income (loss) available to Arch common shareholders |  | $ 978 | $ 713 | $ 3,347 | $ 2,079 |
Underwriting Ratios |  |  |  |  |  |
Loss ratio |  | 60.50% | 50.70% | 54.40% | 50.70% |
Acquisition expense ratio |  | 17.20% | 17.70% | 17.50% | 18.30% |
Other operating expense ratio |  | 8.90% | 9.50% | 9.70% | 10.40% |
Combined ratio |  | 86.60% | 77.90% | 81.60% | 79.40% |
Goodwill and intangible assets |  | $ 1,486 | $ 739 | $ 1,486 | $ 739 | $ 731
Operating segments | Insurance |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Gross premiums written | [2] | 2,341 | 2,043 | 6,569 | 5,977 |
Premiums ceded | [2] | (521) | (521) | (1,649) | (1,564) |
Net premiums written |  | 1,820 | 1,522 | 4,920 | 4,413 |
Change in unearned premiums |  | (55) | (110) | (226) | (416) |
Net premiums earned |  | 1,765 | 1,412 | 4,694 | 3,997 |
Other underwriting income |  | 0 | 0 | 0 | 0 |
Losses and loss adjustment expenses |  | (1,087) | (812) | (2,789) | (2,276) |
Acquisition expenses |  | (308) | (269) | (872) | (778) |
Other operating expenses |  | (250) | (202) | (718) | (592) |
Underwriting income (loss) |  | $ 120 | $ 129 | $ 315 | $ 351 |
Underwriting Ratios |  |  |  |  |  |
Loss ratio |  | 61.60% | 57.50% | 59.40% | 57.00% |
Acquisition expense ratio |  | 17.40% | 19.10% | 18.60% | 19.50% |
Other operating expense ratio |  | 14.10% | 14.30% | 15.30% | 14.80% |
Combined ratio |  | 93.10% | 90.90% | 93.30% | 91.30% |
Goodwill and intangible assets |  | $ 1,025 | $ 220 | $ 1,025 | $ 220 |
Operating segments | Reinsurance |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Gross premiums written | [2] | 2,763 | 2,138 | 9,171 | 7,142 |
Premiums ceded | [2] | (818) | (576) | (3,013) | (2,145) |
Net premiums written |  | 1,945 | 1,562 | 6,158 | 4,997 |
Change in unearned premiums |  | (53) | (19) | (820) | (781) |
Net premiums earned |  | 1,892 | 1,543 | 5,338 | 4,216 |
Other underwriting income |  | 2 | 2 | 5 | 9 |
Losses and loss adjustment expenses |  | (1,317) | (870) | (3,206) | (2,379) |
Acquisition expenses |  | (374) | (304) | (1,050) | (875) |
Other operating expenses |  | (54) | (61) | (193) | (203) |
Underwriting income (loss) |  | $ 149 | $ 310 | $ 894 | $ 768 |
Underwriting Ratios |  |  |  |  |  |
Loss ratio |  | 69.60% | 56.40% | 60.10% | 56.40% |
Acquisition expense ratio |  | 19.80% | 19.70% | 19.70% | 20.70% |
Other operating expense ratio |  | 2.90% | 3.90% | 3.60% | 4.80% |
Combined ratio |  | 92.30% | 80.00% | 83.40% | 81.90% |
Goodwill and intangible assets |  | $ 113 | $ 132 | $ 113 | $ 132 |
Operating segments | Mortgage |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Gross premiums written | [2] | 339 | 347 | 1,020 | 1,037 |
Premiums ceded | [2] | (57) | (76) | (185) | (240) |
Net premiums written |  | 282 | 271 | 835 | 797 |
Change in unearned premiums |  | 31 | 22 | 90 | 86 |
Net premiums earned |  | 313 | 293 | 925 | 883 |
Other underwriting income |  | 3 | 3 | 15 | 12 |
Losses and loss adjustment expenses |  | 1 | 35 | 37 | 46 |
Acquisition expenses |  | 1 | (2) | 1 | (16) |
Other operating expenses |  | (49) | (47) | (151) | (147) |
Underwriting income (loss) |  | $ 269 | $ 282 | $ 827 | $ 778 |
Underwriting Ratios |  |  |  |  |  |
Loss ratio |  | (0.40%) | (12.10%) | (4.00%) | (5.30%) |
Acquisition expense ratio |  | (0.40%) | 0.60% | (0.10%) | 1.80% |
Other operating expense ratio |  | 15.60% | 16.20% | 16.30% | 16.70% |
Combined ratio |  | 14.80% | 4.70% | 12.20% | 13.20% |
Goodwill and intangible assets |  | $ 348 | $ 387 | $ 348 | $ 387 |
[1] | Certain expenses have been excluded from ‘corporate expenses’ and reflected in ‘transaction costs and other.’
[2] | Certain assumed and ceded amounts related to intersegment transactions are included in individual segment results. Accordingly, the sum of such transactions for each segment does not agree to the total due to eliminations.

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- Definition Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from affiliates. + References No definition available. + Details
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- Definition This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 23 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479405/805-10-25-23 + Details
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- Definition Amount of written premiums ceded to other entities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 944 -SubTopic 605 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479032/944-605-50-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 944 -SubTopic 605 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (b)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479032/944-605-50-1 + Details
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