Computation of Weighted Average Shares Outstanding (Parenthetical) (Detail) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Earnings Per Share Disclosure [Line Items]
Potentially dilutive share-based awards	0.8

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.

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Diluted Earnings Per Share

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-Name Accounting Standards Codification

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-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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-Name Accounting Standards Codification

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+ Details