Significant Accounting Policies Common Stock Repurchase Program (Details) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Significant Accounting Policies [Abstract]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 140,000,000
cumulative value of shares repurchased through stock repurchase program	1,000,000,000
cumulative common stock repurchased through repurchase program	29.3
Stock Repurchased During Period, Value	$ 125,000,000	$ 95,000,000
Stock Repurchased During Period, Shares	1.8	1.6

cumulative common stock repurchased through repurchase program

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- Definition

cumulative value of shares repurchased through stock repurchase program

+ References

No definition available.

+ Details

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- Details

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- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

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- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

+ Details

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- Definition

Amount remaining of a stock repurchase plan authorized.

+ References

No definition available.

+ Details

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