Incentive Plan (Summary Of Stock Options Outstanding And Exercisable) (Details) (USD $)	9 Months Ended
Sep. 30, 2012	Dec. 31, 2011
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number outstanding	129,909	337,760
Weighted average remaining contractual life (years), Outstanding	3 years 8 months 12 days
Weighted average exercise price, Outstanding	$ 30.62
Aggregate intrinsic value, Outstanding	$ 5,096,342
Number exercisable	129,909
Weighted average remaining contractual life (years), Exercisable	3 years 8 months 12 days
Weighted average exercise price, Exercisable	$ 30.62
Aggregate intrinsic value, Exercisable	5,096,342
$12.00-13.02 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number outstanding	34,870
Weighted average remaining contractual life (years), Outstanding	2 years 29 days
Weighted average exercise price, Outstanding	$ 12.00
Aggregate intrinsic value, Outstanding	2,017,230
Number exercisable	34,870
Weighted average remaining contractual life (years), Exercisable	2 years 29 days
Weighted average exercise price, Exercisable	$ 12.00
Aggregate intrinsic value, Exercisable	2,017,230
$20.37-28.09 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number outstanding	17,000
Weighted average remaining contractual life (years), Outstanding	3 years 1 month 21 days
Weighted average exercise price, Outstanding	$ 21.28
Aggregate intrinsic value, Outstanding	825,720
Number exercisable	17,000
Weighted average remaining contractual life (years), Exercisable	3 years 1 month 21 days
Weighted average exercise price, Exercisable	$ 21.28
Aggregate intrinsic value, Exercisable	825,720
$33.18-41.73 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number outstanding	78,039
Weighted average remaining contractual life (years), Outstanding	4 years 6 months 15 days
Weighted average exercise price, Outstanding	$ 40.97
Aggregate intrinsic value, Outstanding	2,253,392
Number exercisable	78,039
Weighted average remaining contractual life (years), Exercisable	4 years 6 months 15 days
Weighted average exercise price, Exercisable	$ 40.97
Aggregate intrinsic value, Exercisable	$ 2,253,392
Minimum [Member] \| $12.00-13.02 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price, Exercisable	$ 12.00
Minimum [Member] \| $20.37-28.09 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price, Exercisable	$ 20.37
Minimum [Member] \| $33.18-41.73 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price, Exercisable	$ 33.18
Maximum [Member] \| $12.00-13.02 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price, Exercisable	$ 13.02
Maximum [Member] \| $20.37-28.09 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price, Exercisable	$ 28.09
Maximum [Member] \| $33.18-41.73 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price, Exercisable	$ 41.73

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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- Definition

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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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(c), d(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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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

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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-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

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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- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding.

+ 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 Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph d(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(b)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: 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 3: 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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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(a)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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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

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

+ References

No definition available.

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