Annual report pursuant to Section 13 and 15(d)

Summary of Time-Based Restricted Share Awards' Activity (Detail)

v2.4.0.6
Summary of Time-Based Restricted Share Awards' Activity (Detail) (Restricted Stock, USD $)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Restricted Stock
     
Number of Shares      
Beginning Balance 998,958 321,700 100,000
Granted 1,022,609 1,063,085 274,132
Vested (426,675) (197,990) (51,332)
Forfeited/cancelled (233,945) (187,837) (1,100)
Ending Balance 1,360,947 998,958 321,700
Weighted-Average price      
Beginning of Period $ 24.54 $ 20.54 $ 5.04
Granted $ 19.93 $ 23.92 $ 19.21
Vested $ 23.08 $ 21.48 $ 5.10
Forfeited/cancelled $ 23.34 $ 21.60 $ 27.18
Ending of Period $ 21.58 $ 24.54 $ 20.54