Basis of Presentation (Details) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended 12 Months Ended
Oct. 31, 2012
Jul. 31, 2012
Apr. 30, 2012
Jan. 31, 2012
Oct. 31, 2011
Jul. 31, 2011
Apr. 30, 2011
Jan. 31, 2011
Oct. 31, 2012
Oct. 31, 2011
Oct. 31, 2010
Schedule Of Basis Of Presentation [Line Items]                      
Other revenue                 $ 5,223 $ 4,875 $ 4,541
Total revenue 309,889 298,771 304,770 295,606 297,323 327,056 315,613 308,614 1,209,036 1,248,606 1,115,960
Operating income 106,345 95,016 98,811 92,820 104,648 115,427 106,812 99,345 392,992 426,232 347,581
Gains and other investment income, net                 18,417 19,408 13,046
Net income                 264,768 227,574 201,225
Net income attributable to Eaton Vance Corp. shareholders 53,118 50,206 52,870 47,271 46,820 68,068 62,479 37,535 203,465 214,902 174,298
Dividend income and net investment gains reclassifications         2,700         (11,425) (5,701)
As Previously Reported [Member]
                      
Schedule Of Basis Of Presentation [Line Items]                      
Other revenue                   16,300 10,242
Total revenue                   1,260,031 1,121,661
Operating income                   437,657 353,282
Gains and other investment income, net                   7,983 7,345
Net income                   227,574 201,225
Net income attributable to Eaton Vance Corp. shareholders                   214,902 174,298
As Reclassified [Member]
                      
Schedule Of Basis Of Presentation [Line Items]                      
Other revenue                   4,875 4,541
Total revenue                   1,248,606 1,115,960
Operating income                   426,232 347,581
Gains and other investment income, net                   19,408 13,046
Net income                   227,574 201,225
Net income attributable to Eaton Vance Corp. shareholders                   $ 214,902 $ 174,298