Earnings Per Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Notes to Financial Statements [Abstract]
Net income	$ 148.0	$ 148.0	$ 129.2	$ 257.6	$ 249.6
Average shares outstanding (basic)	245.0		242.9	244.8	243.6
Common stock equivalents	1.9		2.2	2.2	2.4
Incremental shares from assumed conversion of convertible debentures	3.0		1.3	4.1	1.7
Diluted shares	249.9		246.4	251.1	247.7
Basic earnings per share	$ 0.60		$ 0.53	$ 1.05	$ 1.02
Diluted earnings per share	$ 0.59		$ 0.52	$ 1.03	$ 1.01
Interest rate percentage on Convertible Debentures included in calculation of diluted earnings per share, current period (in hundredths)			2.50%		2.50%
Treasury shares acquired (in shares)				2,176,705	3,176,705
Average cost of treasury shares acquired (in dollars per share)			$ 37.59		$ 39.05
Treasury shares issued in satisfaction of stock option exercises and vesting of stock units (in shares)	65,741		1,151,674

Interest rate stated in the contractual debt agreement on outstanding convertible debentures.

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The amount of net income or loss for the period per each share of common stock outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 21
-Article 9

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 36, 37, 38

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-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 20
-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 18
-Article 7

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The amount of net income or loss for the period per each share of common stock and dilutive common stock equivalents outstanding during the reporting period.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 11, 12, 36

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-Name Regulation S-X (SX)
-Number 210
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-Name Regulation S-X (SX)
-Number 210
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Debt securities outstanding shall be assumed to have been converted at the beginning of the period (or at time of issuance, if later), and the resulting common shares shall be included in common shares used to calculate diluted earnings per shares. The dilutive effect of convertible debt securities shall be reflected in diluted Earnings Per Share by application of the if-converted method.

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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 26, 27, 28

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Aggregate awards of share options and nonvested shares to be issued to an employee under a share-based compensation arrangement are considered options for purposes of computing diluted earnings per share. Such share-based awards shall be considered to be outstanding as of the grant date for purposes of computing diluted earnings per share even though their exercise may be contingent upon vesting. Those share-based awards are included in the diluted Earnings Per Share (EPS) computation even if the employee may not receive (or be able to sell) the stock until some future date. Accordingly, all shares to be issued shall be included in computing diluted EPS if the effect is dilutive. The dilutive effect of share-based compensation arrangements shall be computed using the treasury stock method. If the equity share options or other equity instruments are outstanding for only part of a period, the shares issuable shall be weighted to reflect the portion of the period during which the equity instruments were outstanding.

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The portion of consolidated profit or loss for the period, net of income taxes, which is attributable to the parent. If the entity does not present consolidated financial statements, the amount of profit or loss for the period, net of income taxes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 19
-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph d

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-Number 130
-Paragraph 10, 15

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-Name Emerging Issues Task Force (EITF)
-Number 87-21

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Number of treasury shares reissued during the period. Upon reissuance, these are common and preferred shares outstanding.

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Total cost of shares repurchased divided by the total number of shares repurchased.

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-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 1
-Section B
-Paragraph 7
-Subparagraph b

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Number of shares that have been repurchased during the period and are being held in treasury.

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-Name Accounting Principles Board Opinion (APB)
-Number 12
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-Name Regulation S-X (SX)
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The average number of shares issued and outstanding that are used in calculating diluted EPS, determined based on the timing of issuance of shares in the period.

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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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Number of [basic] shares, after adjustment for contingently issuable shares and other shares not deemed outstanding, determined by relating the portion of time within a reporting period that common shares have been outstanding to the total time in that period.

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