| **Share-Based Payments (Tables)**                                                      | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
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| **Disclosure of Compensation Related Costs, Share-based Payments [Abstract]**          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Schedule of Weighted-Average Assumptions Used to Determine Fair Value of Stock Options | The fair values of the options granted during the years ended December 31, 2016, 2015, and 2014 have been estimated at the grant date using the Black-Scholes option-pricing model with the following weighted-average assumptions: For the Year Ended December 31, 2016 2015 2014Expected volatility37.2% 39.5% 40.3%Risk-free interest rate1.6% 1.9% 2.2%Expected life (years)7.5 7.7 7.2Dividend yield2.1% 2.1% 2.1%The fair value of the SARs granted in conjunction with the Encompass acquisition has been estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions: For the Year Ended December 31, 2016 2015Expected volatility25.9% 30.7%Risk-free interest rate1.9% 2.1%Expected life (years)5.3 6.3Dividend yield—% —% |
| Schedule of Stock Option Activity                                                      | A summary of our stock option activity and related information is as follows: Shares(In Thousands) Weighted- Average Exercise Price per Share Weighted- Average Remaining Life (Years) Aggregate Intrinsic Value(In Millions)Outstanding, December 31, 20152,056 $21.37    Granted186 36.15    Exercised(563) 23.14    Forfeitures(102) 37.22    Expirations(2) 24.72    Outstanding, December 31, 20161,575 21.45 4.3 $31.3Exercisable, December 31, 20161,442 19.94 3.9 30.8                                                                                                                                                                                                                                   |
| Schedule of Restricted Stock Activity                                                  | A summary of our issued restricted stock awards is as follows (share information in thousands): Shares Weighted-Average Grant Date Fair ValueNonvested shares at December 31, 2015842 $28.05Granted542 33.56Vested(712) 25.63Forfeited(54) 35.24Nonvested shares at December 31, 2016618 35.06                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |

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| - Definition
Tabular disclosure of the changes in outstanding nonvested restricted stock shares.
+ References
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| - Definition
Tabular disclosure of the number and weighted-average exercise prices (or conversion ratios) for share options (or share units) that were outstanding at the beginning and end of the year, vested and expected to vest, exercisable or convertible at the end of the year, and the number of share options or share units that were granted, exercised or converted, forfeited, and expired during the year.
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| - Definition
Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions.
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