|**Stock-Based Compensation**                   | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
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|**Share-Based Payment Arrangement [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Stock-Based Compensation                       | Stock-Based Compensation The CNAF Incentive Compensation Plan (the Plan) authorizes the grant of stock-based compensation to certain management personnel for up to 16 million shares of CNAF common stock.  The Plan provides for awards of stock options, stock appreciation rights (SARs), restricted shares, restricted stock units (RSUs), performance-based RSUs and performance share units.  Grants to employees are not designed to be spring-loaded.  The number of remaining shares available for the granting of stock-based compensation under the Plan as of December 31, 2023 was approximately 3.6 million.Substantially all of the Company's stock-based compensation is awarded under the Annual Performance Share Plan (PSP).  The PSP provides officers with an opportunity to earn an award based upon attainment of specific performance goals achieved over a one-year performance period.  Awards are granted in the form of performance share units at the beginning of each performance year and are generally subject to a two-year cliff vesting period after the Company’s annual performance has been determined.  The performance share units become payable within a range of 0% to 200% of the number of performance share units initially granted.Additionally, the Company may grant RSUs under the Plan in certain circumstances.  These awards generally vest over a one to three-year service period following the grant date.Stock-based compensation that is not fully vested prior to termination is generally forfeited upon termination, except in cases of retirement, death or disability, and as otherwise provided by contractual obligations.  The fair value of stock-based compensation awards is based on the market value of the Company's common stock as of the date of grant, except for awards made to foreign participants, which is based on the current market value of the Company’s common stock.  Payments made under the PSP are made entirely in shares of common stock granted under the Plan, except for awards made to foreign participants, which are paid in cash.The Company recorded stock-based compensation expense related to the Plan of $38 million,$36 million and $32 million for the years ended December 31, 2023, 2022 and 2021.  The related income tax benefit recognized was $8 million, $8 million and $6 million for the years ended December 31, 2023, 2022 and2021.  The compensation cost not yet recognized was $44 million, and the weighted average period over which it is expected to be recognized is 1.8 years as of December 31, 2023.The total fair value of RSUs and performance share units that vested during the years ended December 31, 2023, 2022 and 2021 was $34 million, $35 million and $36 million, respectively.The weighted average grant date fair value for RSUs and performance share units granted during the years ended December 31, 2023, 2022 and 2021 was $37.06, $46.78 and $45.82, respectively.The following table presents activity for non-vested RSUs and performance share units under the Plan in 2023.Number of AwardsWeighted Average Grant Date Fair ValueBalance as of January 1, 20232,465,752$43.10Awards granted1,437,60537.06Awards vested(950,620)38.06Awards forfeited, canceled or expired(478,823)42.28Performance-based adjustment152,39936.87Balance as of December 31, 20232,626,31341.40
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|                                               | Number of Awards                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Balance as of January 1, 2023                  | 2,465,752                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Awards granted                                 | 1,437,605                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Awards vested                                  | (950,620)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Awards forfeited, canceled or expired          | (478,823)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
|Performance-based adjustment                   | 152,399                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Balance as of December 31, 2023                | 2,626,313                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                

X- DefinitionThe entire disclosure for share-based payment arrangement.
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