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Preferred and Common Stock - Schedule of Share Activity (Detail) |  |  |  |  | 12 Months Ended
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Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009 | Dec. 31, 2012 Outstanding Stock [Member] | Dec. 31, 2011 Outstanding Stock [Member] | Dec. 31, 2010 Outstanding Stock [Member] | Dec. 31, 2012 Treasury Stock [Member] | Dec. 31, 2011 Treasury Stock [Member] | Dec. 31, 2010 Treasury Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |
Treasury stock, beginning balance | 110,694,604 | 113,494,491 | 119,362,029 | 122,695,718 |  |  |  |  |  |
Private placement |  |  |  |  |  | 36,518,563 | 44,313,146 |  |  |
Conversion of convertible notes |  |  |  |  |  |  | 310 |  |  |
Issued for stock-based compensation plans |  |  |  |  | 2,799,887 | 5,867,538 | 3,333,689 | (2,799,887) | (5,867,538) | (3,333,689)
Treasury stock, ending balance | 110,694,604 | 113,494,491 | 119,362,029 | 122,695,718 |  |  |  |  |  |
Common Stock Outstanding, beginning balance | 1,067,211,953 | 1,064,412,066 | 1,022,025,965 | 974,378,820 |  |  |  |  |  |
Common Stock Outstanding, ending balance | 1,067,211,953 | 1,064,412,066 | 1,022,025,965 | 974,378,820 |  |  |  |  |  |

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