Stock Based Compensation - Options Summary (Details) (USD $)	9 Months Ended
Sep. 30, 2012
$0.00 - $10.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 0.00
Exercise Price Range, Upper Range Limit	$ 10.00
Number of Outstanding Options, Exercise Price Range	9,551
Weighted Average Contractual Life, Outstanding Options, Exercise Price Range	3 years 5 months
Weighted Average Exercise Price, Outstanding Options, Exercise Price Range	$ 6.93
Number of Exercisable Options, Exercise Price Range	9,551
Weighted Average Exercise Price, Exercisable Options, Exercise Price Range	$ 6.93
$10.01 - $20.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 10.01
Exercise Price Range, Upper Range Limit	$ 20.00
Number of Outstanding Options, Exercise Price Range	38,139
Weighted Average Contractual Life, Outstanding Options, Exercise Price Range	4 years 2 months
Weighted Average Exercise Price, Outstanding Options, Exercise Price Range	$ 18.85
Number of Exercisable Options, Exercise Price Range	8,073
Weighted Average Exercise Price, Exercisable Options, Exercise Price Range	$ 18.97
$20.01 - $30.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 20.01
Exercise Price Range, Upper Range Limit	$ 30.00
Number of Outstanding Options, Exercise Price Range	0
Weighted Average Contractual Life, Outstanding Options, Exercise Price Range	0 years
Weighted Average Exercise Price, Outstanding Options, Exercise Price Range	$ 0
Number of Exercisable Options, Exercise Price Range	0
Weighted Average Exercise Price, Exercisable Options, Exercise Price Range	$ 0
$30.01 - $40.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 30.01
Exercise Price Range, Upper Range Limit	$ 40.00
Number of Outstanding Options, Exercise Price Range	68,122
Weighted Average Contractual Life, Outstanding Options, Exercise Price Range	5 years 11 months
Weighted Average Exercise Price, Outstanding Options, Exercise Price Range	$ 37.76
Number of Exercisable Options, Exercise Price Range	10,285
Weighted Average Exercise Price, Exercisable Options, Exercise Price Range	$ 37.37
$40.01 - $50.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 40.01
Exercise Price Range, Upper Range Limit	$ 50.00
Number of Outstanding Options, Exercise Price Range	2,192
Weighted Average Contractual Life, Outstanding Options, Exercise Price Range	6 years 10 months
Weighted Average Exercise Price, Outstanding Options, Exercise Price Range	$ 46.21
Number of Exercisable Options, Exercise Price Range	0
Weighted Average Exercise Price, Exercisable Options, Exercise Price Range	$ 0
Total
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Outstanding Options, Exercise Price Range	118,004
Weighted Average Contractual Life, Outstanding Options, Exercise Price Range	5 years 2 months
Weighted Average Exercise Price, Outstanding Options, Exercise Price Range	$ 29.31
Number of Exercisable Options, Exercise Price Range	27,909
Weighted Average Exercise Price, Exercisable Options, Exercise Price Range	$ 21.63

Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

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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 Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64

-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

-Subparagraph (g)

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

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- Definition

The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

+ 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)(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.

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)(iii)

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

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- Definition

The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

+ 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)-(ii)

-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 b(1)(a, 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.

+ Details

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- Definition

The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

+ References

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- Definition

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

+ References

+ Details

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- Definition

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

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