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Stockholders' Equity and Statutory Accounting Practices (Tables) | 12 Months Ended
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Dec. 31, 2017
Stockholders' Equity and Statutory Accounting Practices [Abstract] |
Combined statutory capital and surplus and net income (loss) | Combined statutory capital and surplus and statutory net income (loss) for the Combined Continental Casualty Companies are presented in the table below, determined in accordance with accounting practices prescribed or permitted by insurance and/or other regulatory authorities
| Statutory Capital and Surplus |  | Statutory Net Income (Loss)
| December 31 |  | Years ended December 31
(In millions) | 2017 (1) |  | 2016 |  | 2017 (1) |  | 2016 |  | 2015
Combined Continental Casualty Companies | $ | 10,726 |  |  | $ | 10,748 |  |  | $ | 1,029 |  |  | $ | 1,033 |  |  | $ | 1,148 |
(1) Information derived from the statutory-basis financial statements to be filed with insurance regulators.

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