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Earnings Per Share | 3 Months Ended
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Mar. 31, 2013
Earnings Per Share [Abstract] |
Earnings Per Share | 12. E ARNINGS P ER COMMON SHARE (EPS) Basic Earnings Per Share (EPS) is computed by dividing net income attributable to Duke Energy common shareholders, adjusted for distributed and undistributed earnings allocated to participating securities, by the weighted-average number of common shares outstanding during the period. Diluted EPS is computed by dividing net income attributable to Duke Energy common shareholders, as adjusted for distributed and undistributed earnings allocated to participating securities, by the diluted weighted-average number of common shares outstanding during the period. Diluted EPS reflects the potential dilution that could occur if securities or other agreements to issue common stock, such as stock options, phantom shares and stock-based performance unit awards were exercised or settled. On July 2, 2012, just prior to the close of the merger with Progress Energy, Duke Energy executed a one-for-three reverse stock split. All earnings per share amounts included in this Form 10-Q are presented as if the one-for-three reverse stock split had been effective January 1, 201 2. The following table presents Duke Energy's basic and diluted EPS calculations and reconciles the weighted-average number of common shares outstanding to the diluted weighted-average number of common shares outstandin g.
(In millions, except per-share amounts) | Income |  | Average Shares |  | EPS
Three Months Ended March 31, 2013 |  |  |  |  |  |  |  |
Income from continuing operations attributable to Duke Energy common shareholders, as adjusted for participating securities — basic and diluted | $ | 629 |  |  | 705 |  | $ | 0.89
Three Months Ended March 31, 2012 |  |  |  |  |  |  |  |
Income from continuing operations attributable to Duke Energy common shareholders, as adjusted for participating securities — basic and diluted | $ | 292 |  |  | 446 |  | $ | 0.65
As of March 31, 2013, and 2012, 1 million of stock options and performance and unvested stock awards were not included in the dilutive securities calculation in the above table because either the option exercise prices were greater than the average market price of the common shares during those periods, or performance measures related to the awards had not yet been met.

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- Definition The entire disclosure for earnings per share. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1252-109256 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 55 -Paragraph 52 -URI http://asc.fasb.org/extlink&oid=16381557&loc=d3e4984-109258 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1278-109256 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 128 -Paragraph 40 -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 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.21) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 + Details
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