Annual report pursuant to Section 13 and 15(d)

Equity Structure and Transactions - Additional Information (Detail)

v2.4.0.6
Equity Structure and Transactions - Additional Information (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified
12 Months Ended 1 Months Ended 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Feb. 26, 2013
Subsequent Event
Dec. 31, 2012
Common Stock, Regular
Dec. 31, 2011
Common Stock, Regular
Dec. 31, 2010
Common Stock, Regular
Dec. 31, 2012
Common Stock, Special
Dec. 31, 2011
Common Stock, Special
Dec. 31, 2010
Common Stock, Special
Equity Structure And Transactions [Line Items]                  
Preferred stock, shares authorized 20,000,000 2,000,000              
Preferred stock, par value $ 0.00001 $ 0.00001              
Paid cash dividends, per share       $ 0.32 $ 0.16 $ 0.14 $ 0.79 $ 0.63 $ 0.66
Cash dividends       $ 23,798 $ 11,913 $ 10,446 $ 59,034 $ 46,842 $ 49,132
Dividends declared, per common share     $ 0.08            
Dividend payable date Mar. 29, 2013                
Dividend record date Mar. 15, 2013