Share-Based Compensation (Additional Information Option Outstanding) (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding	1,863,800	1,944,100
Weighted Average Exercise Price	$ 33.12	$ 33.18
Weighted Average Remaining Contractual Life	4 years 8 months 1 day	6 years 1 month 0 days
Options Exercisable	1,580,100
Weighted Average Exercise Price	$ 32.89
$0 - $14 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding	61,100
Weighted Average Exercise Price	$ 11.95
Weighted Average Remaining Contractual Life	0 years 1 month 6 days
Options Exercisable	61,100
Weighted Average Exercise Price	$ 11.95
Range of Option Prices, Lower Range Limit	$ 0
Range of Option Prices, Upper Range Limit	$ 14
$14 - $28 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding	742,900
Weighted Average Exercise Price	$ 21.79
Weighted Average Remaining Contractual Life	3 years 5 months
Options Exercisable	742,900
Weighted Average Exercise Price	$ 21.79
Range of Option Prices, Lower Range Limit	$ 14
Range of Option Prices, Upper Range Limit	$ 28
$28 - $42 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding	599,000
Weighted Average Exercise Price	$ 33.90
Weighted Average Remaining Contractual Life	7 years 3 months 12 days
Options Exercisable	315,300
Weighted Average Exercise Price	$ 33.47
Range of Option Prices, Lower Range Limit	$ 28
Range of Option Prices, Upper Range Limit	$ 42
$42 - $56 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding	267,700
Weighted Average Exercise Price	$ 45.15
Weighted Average Remaining Contractual Life	4 years 8 months 24 days
Options Exercisable	267,700
Weighted Average Exercise Price	$ 45.15
Range of Option Prices, Lower Range Limit	$ 42
Range of Option Prices, Upper Range Limit	$ 56
$56 - $70 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding	193,100
Weighted Average Exercise Price	$ 64.27
Weighted Average Remaining Contractual Life	2 years 11 months
Options Exercisable	193,100
Weighted Average Exercise Price	$ 64.27
Range of Option Prices, Lower Range Limit	$ 56
Range of Option Prices, Upper Range Limit	$ 70

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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

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)(1)(iii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

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

+ Details

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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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option 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)(1)(i)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

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.

+ 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 (e)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ 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 (g)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ 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 (g)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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