Investment Securities - Company's Investment Securities Holdings (Detail) (USD $)
In Thousands, unless otherwise specified
9 Months Ended 12 Months Ended
Sep. 30, 2012
Dec. 31, 2011
Investment Holdings [Line Items]    
Cost $ 606 $ 606
Unrealized Gains 2 4
Unrealized Losses      
Fair Value 608 610
Fair Value 12,022 4,032
Total investment securities 12,630 4,642
Equity securities [Member]
   
Investment Holdings [Line Items]    
Fair Value 5,689 2,656
Fixed income securities [Member]
   
Investment Holdings [Line Items]    
Fair Value 5,014  
Short-term securities [Member]
   
Investment Holdings [Line Items]    
Fair Value 1,111 636
Managed mutual funds [Member]
   
Investment Holdings [Line Items]    
Fair Value 208 740
US Treasury Note (0.375%, 9/30/2012) [Member]
   
Investment Holdings [Line Items]    
Percentage of Notes 0.375% 0.375%
Cost 504 504
Unrealized Gains 2 2
Unrealized Losses      
Fair Value 506 506
US Treasury Note (1.75%, 1/31/2014) [Member]
   
Investment Holdings [Line Items]    
Percentage of Notes 1.75% 1.75%
Cost 102 102
Unrealized Gains   2
Unrealized Losses      
Fair Value $ 102 $ 104