Share-Based Compensation Plans Summary of information about stock options (Details) (USD $)	12 Months Ended
Dec. 31, 2012
$9.67 - $10.96
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	$ 9.67
Range of Exercise Prices, Upper Range	$ 10.96
Stock Options Outstanding and Exercisable, Number (in shares)	425,396
Stock Options Outstanding and Exercisable, Weighted Average Remaining Life	1 year 2 months 1 day
Stock Options Outstanding and Exercisable, Weighted Average Exercise Price	$ 10.70
$11.01 - $12.49
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	$ 11.01
Range of Exercise Prices, Upper Range	$ 12.49
Stock Options Outstanding and Exercisable, Number (in shares)	657,200
Stock Options Outstanding and Exercisable, Weighted Average Remaining Life	2 years 4 days
Stock Options Outstanding and Exercisable, Weighted Average Exercise Price	$ 11.36
$20.42 - $22.53
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	$ 20.42
Range of Exercise Prices, Upper Range	$ 22.53
Stock Options Outstanding and Exercisable, Number (in shares)	220,000
Stock Options Outstanding and Exercisable, Weighted Average Remaining Life	4 years 7 days
Stock Options Outstanding and Exercisable, Weighted Average Exercise Price	$ 21.29
$23.17 - $29.26
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	$ 23.17
Range of Exercise Prices, Upper Range	$ 29.26
Stock Options Outstanding and Exercisable, Number (in shares)	373,781
Stock Options Outstanding and Exercisable, Weighted Average Remaining Life	4 years 7 months 17 days
Stock Options Outstanding and Exercisable, Weighted Average Exercise Price	$ 26.18
$36.03
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Range	$ 36.03
Stock Options Outstanding and Exercisable, Number (in shares)	120,000
Stock Options Outstanding and Exercisable, Weighted Average Remaining Life	2 years 5 months 19 days
Stock Options Outstanding and Exercisable, Weighted Average Exercise Price	$ 36.03

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

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 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

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

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 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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