Related Party Transactions (Tables)
 6 Months Ended
Apr. 30, 2017
Related Party Transactions Disclosure Table [Abstract]  
Summary of related party revenue transactions
   Three Months Ended Six Months Ended
   April 30, April 30,
 (in thousands) 2017 2016 2017 2016
 Management fees$ 226,959$ 193,851$ 441,708$ 395,398
 Distribution fees  18,998  16,506  37,279  33,939
 Service fees  30,067  25,794  58,978  53,053
 Shareholder services fees  1,271  629  1,973  1,217
 Other revenue  576  712  1,090  1,249
 Total$ 277,871$ 237,492$ 541,028$ 484,856
Summary of sales proceeds and net realized gains earned on investments in sponsored funds classified as available-for-sale, including sponsored funds accounted for under the equity method
   Three Months Ended Six Months Ended
   April 30, April 30,
 (in thousands) 2017 2016 2017 2016
 Proceeds from sales $ 1$ 214$ 3,734$ 8,298
 Net realized gains  -  27  203  162