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Earnings Per Share - Additional Information (Detail)
In Millions
3 Months Ended9 Months Ended
Sep. 30, 2011
Sep. 30, 2010
Sep. 30, 2011
Sep. 30, 2010
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]    
Options to purchase shares, restricted share awards, common stock warrants and contingently issuable shares excluded from diluted earnings per share computation3.25.53.25.5