Stock-Based Compensation Plans (Details 3) (USD $) In Millions, except Per Share data, unless otherwise specified	6 Months Ended
Jun. 30, 2012
Performance Share Awards
Stock-Based Compensation Plans - Disclosures
Awards or units granted (in shares)	0.4
Awards or units granted weighted-average grant-date fair value (in dollars per share)	$ 27.46
Other award and unit disclosures
Lower limit multiple of initial target awards (as a percent)	0.00%
Upper limit multiple of initial target awards (as a percent)	150.00%
Unrecognized compensation costs	$ 10.0
Weighted-average service period over which unrecognized compensation costs will be recognized	1 year 7 months 6 days
Restricted Stock Units
Stock-Based Compensation Plans - Disclosures
Awards or units granted (in shares)	1.1
Awards or units granted weighted-average grant-date fair value (in dollars per share)	$ 27.33
Other award and unit disclosures
Unrecognized compensation costs	$ 46.8
Weighted-average service period over which unrecognized compensation costs will be recognized	2 years

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The lower limit multiple of initial target awards which will be used to determine the actual number of shares to be awarded at the end of each performance period for performance-based awards.

+ References

No definition available.

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- Definition

The upper limit multiple of initial target awards which will be used to determine the actual number of shares to be awarded at the end of each performance period for performance-based awards.

+ References

No definition available.

+ Details

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- Definition

As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

+ References

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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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

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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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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(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.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Paragraph A240

-Subparagraph b(2)(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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