Stock-Based Compensation Plans (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015
Performance Share Awards
Change in nonvested units outstanding
Awards or units granted (in shares)	300,000
Awards or units granted weighted-average grant-date fair value (in dollars per share)	$ 51.33
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	$ 16.7
Weighted-average service period over which unrecognized compensation costs will be recognized	1 year 8 months 12 days
Restricted Stock Units
Change in nonvested units outstanding
Awards or units granted (in shares)	800,000
Awards or units granted weighted-average grant-date fair value (in dollars per share)	$ 51.32
Other award and unit disclosures
Unrecognized compensation costs	$ 73.9
Weighted-average service period over which unrecognized compensation costs will be recognized	2 years 2 months 12 days

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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.

+ Details

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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

Unrecognized cost of unvested share-based compensation awards.

+ 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 (i)

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

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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

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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