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Earning Per Share - Additional Information (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2012 | Jun. 30, 2012 | Jun. 30, 2011
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |
Participating securities outstanding, maximum | 1 | 1 | 2
Stock And Performance Awards |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |
Participating securities outstanding, nonforfeitable | 12 | 12 | 7
Equity Unit Purchase Agreements |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |
Number of anti-dilutive securities |  | 28 | 19
Stock options |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |
Shares that would have been included in diluted earnings per share calculation | 19 |  |
Number of anti-dilutive securities | 4 |  |
Weighted average exercise price of options |  | $ 15.44 | $ 28.61
Convertible notes |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |
Shares that would have been included in diluted earnings per share calculation | 89 |  |
Number of anti-dilutive securities | 89 | 89 |
Stock awards |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |
Shares that would have been included in diluted earnings per share calculation | 12 |  |
Number of anti-dilutive securities | 6 |  |

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- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Emerging Issues Task Force (EITF) -Number 07-4 -Paragraph 4 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Diluted Earnings Per Share -URI http://asc.fasb.org/extlink&oid=6510752 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Contingent Stock Agreement -URI http://asc.fasb.org/extlink&oid=6508534 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Antidilution -URI http://asc.fasb.org/extlink&oid=6505113 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 128 -Paragraph 171 -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 Statement of Financial Accounting Standard (FAS) -Number 128 -Paragraph 40 -Subparagraph c -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 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 128 -Paragraph 13, 14 -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. + Details
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