Summary of Significant Accounting Policies - Weighted Average Number of Common and Common Equivalent Shares Used in Calculation of Basic and Diluted Earnings Per Share (Detail)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted average common shares outstanding (used in the calculation of basic earnings per share)	806,395,660	728,343,428	667,463,535
Potential dilution from stock options, warrants and restricted stock and stock units	18,160,376	83,473,259	124,297,089
Weighted average common and common equivalent shares (used in the calculation of diluted earnings per share)	824,556,036	811,816,687	791,760,624
Antidilutive stock options excluded from the calculation of diluted earnings per share	4,700,981	5,493,706	9,848,266

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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+ Details

- Definition

The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

+ References+ Details

- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References+ Details

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

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+ Details