Quarterly report pursuant to Section 13 or 15(d)

Roll-forward of Common Stock, Additional Paid-in Capital, and Retained Earnings Accounts (Parenthetical) (Detail)

v2.3.0.15
Roll-forward of Common Stock, Additional Paid-in Capital, and Retained Earnings Accounts (Parenthetical) (Detail) (Retained Earnings, USD $)
9 Months Ended
Sep. 30, 2011
Sep. 30, 2010
Retained Earnings
   
Stockholders Equity Note [Line Items]    
Dividends, per share $ 1.56 $ 1.41