Stock Based Compensation - Options Rollforward (Details) (USD $)	3 Months Ended
Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning Balance	87,075
Options Granted	38,698
Options Exercised	(5,335)
Ending Balance	120,438
Options Exerciseable	46,549
Weighted Average Exercise Price [Abstract]
Outstanding at Beginning of Year	$ 59.09
Options Granted	$ 87.3
Options Exercised	$ 45.26
Outstanding at End of Period	$ 68.77
Options Exercisable	$ 53.43
Weighted Average Contractual Term [Abstract]
Weighted Average Remaining Contractual Term, Outstanding	5 years 8 months
Weighted Average Remaining Contractual Term, Exercisable	4 years 8 months

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

+ References

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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Gross number of share options (or share units) granted during the period.

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No definition available.

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- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

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

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Weighted average price at which option holders acquired shares when converting their stock options into shares.

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No definition available.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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No definition available.

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Number of share options (or share units) exercised during the current period.

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-Name Regulation S-X (SX)

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