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Share-Based Compensation and Other Compensation Matters (Details 4) - Performance share units [Member] - $ / shares | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Potential earned PSUs payout for defined levels of performance under awards |  |  |
Earned PSUs payout (as a percent of PSUs granted) on 75th or greater percentile rank | 200.00% |  |
Earned PSUs payout (as a percent of PSUs granted) on 50th percentile rank | 100.00% |  |
Earned PSUs payout (as a percent of PSUs granted) on 25th percentile rank | 50.00% |  |
Performance share units granted on percentile rank below 25th (as a percent) | 0.00% |  |
Assumptions used to value stock awards |  |  |
Grant date fair value (in dollars per share) | $ 38.21 | $ 36.76 | $ 35.09
Baseline value per common share (in dollars per share) | $ 23.90 | $ 29.28 | $ 26.52
Expected volatility of common shares (as a percent) | 20.40% | 19.90% | 28.60%
Risk-free interest rate (as a percent) | 0.96% | 0.99% | 0.66%

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- Definition Represents the baseline common share value that is used in valuing the grant date fair value of awards. + References No definition available. + Details
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- Definition Represents the earned performance share units payout, as a percentage of performance share units granted, if the entity's total shareholder return relative to a peer group of companies ranks at the 25th percentile. + References No definition available. + Details
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- Definition Represents the earned performance share units payout, as a percentage of performance share units granted, if the entity's total shareholder return relative to a peer group of companies ranks at the 50th percentile. + References No definition available. + Details
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- Definition Represents the earned performance share units payout, as a percentage of performance share units granted, if the entity's total shareholder return relative to a peer group of companies ranks at the 75th percentile or greater. + References No definition available. + Details
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- Definition Represents the earned performance share units payout percentage based on percentile rank below 25. + References No definition available. + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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