Non-Vested Shares of Restricted Common Stock (Detail) (USD $)
In Thousands, except Per Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Shares      
Non-vested at December 31, 2012 87    
Granted 41    
Vested (25)    
Forfeited (10)    
Non-vested at December 31, 2013 93    
Weighted average grant date fair value:      
Weighted average grant date fair value, Beginning Balance $ 51.30    
Granted $ 15.82    
Vested $ 52.87    
Forfeited $ 47.43    
Weighted average grant date fair value, Ending Balance $ 35.64    
Restricted Stock Units
     
Shares      
Granted 62 0 0
Vested 0    
Forfeited (6)    
Non-vested at December 31, 2013 56    
Weighted average grant date fair value:      
Granted $ 34.40    
Forfeited $ 36.30    
Weighted average grant date fair value, Ending Balance $ 35.64