v2.4.0.8
Stockholders' Equity (Details 3) (Options, USD $)
 12 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2010
Options
        
Stock option activity        
Options outstanding at the beginning of the period (in shares) 1,675,795 2,894,547    
Options granted (in shares) 171,994 181,783 321,072 624,566
Options exercised (in shares) (223,139) (1,322,387)    
Options cancelled (in shares) (32,244) (78,148) (73,591) (75,467)
Options outstanding at the end of the period (in shares) 1,592,406 1,675,795 2,894,547  
Options exercisable at the end of the period (in shares) 1,161,779      
Weighted-Average Exercise Price        
Options outstanding at the beginning of the period (in dollars per share) $ 13.84 $ 11.55    
Options granted (in dollars per share) $ 35.76 $ 34.42    
Options exercised (in dollars per share) $ 11.35 $ 11.72    
Options cancelled (in dollars per share) $ 18.67 $ 12.72    
Options outstanding at the end of the period (in dollars per share) $ 16.46 $ 13.84 $ 11.55  
Options exercisable at the end of the period (in dollars per share) $ 13.48