Earnings Per Share (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
3 Months Ended 12 Months Ended
Oct. 31, 2011
Jul. 31, 2011
Apr. 30, 2011
Jan. 31, 2011
Oct. 31, 2010
Jul. 31, 2010
Apr. 30, 2010
Jan. 31, 2010
Oct. 31, 2011
Oct. 31, 2010
Oct. 31, 2009
Earnings Per Share Reconciliation [Abstract]                      
Net income attributable to Eaton Vance Corp. shareholders $ 46,820 $ 68,068 $ 62,479 $ 37,535 $ 50,306 $ 41,750 $ 36,000 $ 46,242 $ 214,902 $ 174,298 $ 130,107
Net income allocated to participating restricted shares                 4,597 2,675 1,125
Net income allocated to common shares (basic)                 210,305 171,623 128,982
Net income allocated to common shares (diluted)                 $ 210,305 $ 171,623 $ 128,982
Weighted-average shares outstanding - basic                 115,326,000 116,444,000 116,175,000
Incremental common shares                 4,649,000 6,188,000 4,400,000
Weighted-average shares outstanding - diluted                 119,975,000 122,632,000 120,575,000
Earnings per common share attributable to Eaton Vance Corp. shareholders (Basic) ($ per share) $ 0.41 $ 0.58 $ 0.53 $ 0.31 $ 0.43 $ 0.35 $ 0.30 $ 0.39 $ 1.82 $ 1.47 $ 1.11
Earnings per common share attributable to Eaton Vance Corp. shareholders (Diluted) ($ per share) $ 0.40 $ 0.55 $ 0.50 $ 0.30 $ 0.41 $ 0.34 $ 0.29 $ 0.37 $ 1.75 $ 1.40 $ 1.07
Antidilutive common shares                 12,100,000 9,000,000 14,600,000