Share-based Compensation (Details 2) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Analysis of SARs outstanding
Forfeiture Rate on unvested SARs	4.00%	2.00%
SAR Two Thousand Fourteen Grant [Member]
Analysis of SARs outstanding
SARs outstanding (in shares)	86,419
Vested and exercisable (in shares)	0
Vesting period	3 years
Weighted average exercise price (in dollars per share)	49.76
Expected dividend yield	3.10%
Forfeiture Rate on unvested SARs	4.00%
SAR Two Thousand Fourteen Grant [Member] \| Minimum [Member]
Analysis of SARs outstanding
Expected volatility range	44.20%
Expected life range (in years)	3 years 1 month 6 days
Risk-free interest rate	1.10%
SAR Two Thousand Fourteen Grant [Member] \| Maximum [Member]
Analysis of SARs outstanding
Expected volatility range	52.80%
Expected life range (in years)	4 years 6 months
Risk-free interest rate	1.70%
2012 Grant [Member]
Analysis of SARs outstanding
SARs outstanding (in shares)	38,327
Vested and exercisable (in shares)	733
Vesting period	3 years
Weighted average exercise price (in dollars per share)	29.31
Expected volatility range	42.70%
Risk-free interest rate	0.70%
Expected dividend yield	3.10%
Forfeiture Rate on unvested SARs	4.00%
2012 Grant [Member] \| Minimum [Member]
Analysis of SARs outstanding
Expected life range (in years)	2 years
2012 Grant [Member] \| Maximum [Member]
Analysis of SARs outstanding
Expected life range (in years)	2 years 1 month 6 days
2011 Grant [Member]
Analysis of SARs outstanding
SARs outstanding (in shares)	9,632
Vested and exercisable (in shares)	9,632
Vesting period	3 years
Weighted average exercise price (in dollars per share)	24.45
Expected volatility range	42.50%
Expected life range (in years)	1 year 8 months 12 days
Risk-free interest rate	0.70%
Expected dividend yield	3.10%
2010 Grant [Member]
Analysis of SARs outstanding
SARs outstanding (in shares)	2,283
Vested and exercisable (in shares)	2,283
Vesting period	3 years
Weighted average exercise price (in dollars per share)	12.80
Expected volatility range	46.00%
Risk-free interest rate	0.20%
Expected dividend yield	3.10%
2010 Grant [Member] \| Minimum [Member]
Analysis of SARs outstanding
Expected life range (in years)	1 year 1 month 6 days
2010 Grant [Member] \| Maximum [Member]
Analysis of SARs outstanding
Expected life range (in years)	1 year 2 months
2009 Grant [Member]
Analysis of SARs outstanding
SARs outstanding (in shares)	2,350
Vested and exercisable (in shares)	2,350
Vesting period	4 years
Weighted average exercise price (in dollars per share)	6.71
Expected volatility range	46.30%
Expected life range (in years)	7 months 6 days
Risk-free interest rate	0.20%
Expected dividend yield	3.10%
2008 Grant [Member]
Analysis of SARs outstanding
SARs outstanding (in shares)	100
Vested and exercisable (in shares)	100
Vesting period	4 years
Weighted average exercise price (in dollars per share)	20.88
Expected volatility range	46.30%
Expected life range (in years)	2 months
Risk-free interest rate	0.20%
Expected dividend yield	3.10%

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Share based compensation arrangement by share based payment award equity instruments other than options vested and exercisable.

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Share based compensation arrangement by share based payment award fair value assumptions forfeiture rate for unvested shares that are outstanding.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Agreed-upon price for the exchange of the underlying asset relating to the share-based payment award.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 14.D.2)

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-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section D

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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.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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