Stock-Based Plans (Details) (USD $)	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012
Restricted stock units and restricted shares \| Executives and directors
Stock Plans
Share-based compensation arrangement by share-based payment award, restricted stock units and restricted shares (in shares)	477,731	450,668
Share-based compensation arrangement by share-based payment award, restricted stock units and restricted shares, weighted-average per share price (in dollars per share)	$ 61.45	$ 61.70
Restricted stock units \| Executives
Stock Plans
Share-based compensation arrangement by share-based payment award, award vesting period	3 years	3 years
Restricted shares \| Executives
Stock Plans
Share-based compensation arrangement by share-based payment award, award vesting period	3 years	3 years
Stock Options \| Executives
Stock Plans
Share-based compensation arrangement by share-based payment award, options awarded (in shares)	884,574	688,380
Share-based compensation arrangement by share-based payment award, options awarded weighted average exercise price (in dollars per share)	$ 61.45	$ 62.18
Share-based compensation arrangement by share-based payment award, award vesting period	3 years	3 years
Share-based compensation arrangement by share-based payment award, award expiration period	10 years	10 years
Performance-based VDI units \| Executives
Stock Plans
Share-based compensation arrangement by share-based payment award, restricted stock units and restricted shares (in shares)	385,742	341,104
Share-based compensation arrangement by share-based payment award, restricted stock units and restricted shares, weighted-average per share price (in dollars per share)	$ 61.45	$ 62.29
Share-based compensation arrangement by share-based payment award, award vesting period	3 years

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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

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

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- Definition

The number of grants made 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

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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

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Balance Type:	na
Period Type:	duration

- Definition

Period from grant date that an equity-based award expires, 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 (a)(2)

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

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Net number of share options (or share units) granted during 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 (c)(1)(iv)(1)

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

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- Definition

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

+ References

No definition available.

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