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Repurchases of Outstanding Securities (Details) (USD $) | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Dec. 31, 2013 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Sep. 30, 2013 | Dec. 31, 2012
Accelerated Stock Buyback (Details) [Abstract] |  |  |  |  |  |
Accelerated stock buyback, gross price paid |  |  | $ 200,000,000 |  |  |
Accelerated stock buyback, initial shares delivered (shares) |  |  | 4,592,423 |  |  |
Accelerated stock buyback, value of initial shares delivered |  |  | 160,000,000 |  |  |
Accelerated stock buyback, additional shares delivered at settlement (shares) | 816,916 |  |  |  |  |
Accelerated stock buyback, value of final settlement | 40,000,000 |  |  |  |  |
Repurchases of Outstanding Securities (Details) [Abstract] |  |  |  |  |  |
Authorized aggregate amount |  |  |  |  | 1,250,000,000 |
Total number of shares repurchased since inception of our stock repurchase program (shares) |  |  |  |  | 36,177,737 | 31,120,279
Aggregate purchase price of shares repurchased since inception of our stock repurchase program |  |  |  |  | 994,800,000 | 777,300,000
Number of shares repurchased (shares) |  | 0 |  | 465,035 |  |
Purchase price of shares repurchased |  |  |  | $ 17,400,000 |  |

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- Definition Number of shares that have been repurchased and retired during the period. + 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 + Details
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