Annual report pursuant to Section 13 and 15(d)

Summary of Company's Treasure Stock Activity (Parenthetical) (Detail)

v2.4.0.6
Summary of Company's Treasure Stock Activity (Parenthetical) (Detail) (USD $)
12 Months Ended
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Common stock repurchased value as result of restricted stock forfeitures and canceled $ 0.001
Maximum
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Market Value of Restricted Shares $ 22.50
Minimum
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Market Value of Restricted Shares $ 19.60