| **Earnings (Loss) Per Share**     | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
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| **Earnings Per Share [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| Earnings (Loss) Per Share         | Note B. Earnings (Loss) Per ShareEarnings (loss) per share is based on weighted average number of outstanding common shares.  Basic earnings (loss) per share excludes the impact of dilutive securities and is computed by dividing Net income (loss) by the weighted average number of common shares outstanding for the period.  Diluted earnings (loss) per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock.For the three months ended March 31, 2022 and 2021, approximately 1.1 million and 1.0 million potential shares attributable to exercises or conversions into common stock under stock-based employee compensation plans were included in the calculation of diluted earnings per share.  For those same periods, less than 1 thousand and approximately 120 thousand potential shares attributable to exercises or conversions into common stock under stock-based employee compensation plans were not included in the calculation of diluted earnings per share, because the effect would have been antidilutive. The Company repurchased 445,000 and 66,000 shares of CNAF common stock at an aggregate cost of $21 million and $3 million during the three months ended March 31, 2022 and 2021. |

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| - Definition
The entire disclosure for earnings per share.
+ References
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