Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Voting Common Stock [Member]	Non-Voting Common Stock [Member]	Additional Paid-In Capital [Member]	Notes Receivable From Stock Option Exercises [Member]	Accumulated Other Comprehensive Loss [Member]	Appropriated Deficit [Member]	Retained Earnings [Member]	Non-Redeemable Non-Controlling Interests [Member]	Total Permanent Equity [Member]	Redeemable Non-Controlling Interests [Member]
Beginning balance, at Oct. 31, 2015		$ 2	$ 451	$ 0	$ (11,143)	$ (48,586)	$ (5,338)	$ 684,845	$ 1,725	$ 621,956	$ 88,913
Net income	$ 132,687						12,701	113,353	1,863	127,917	4,770
Other comprehensive income (loss)	7,730					7,730				7,730
Dividends declared								(60,495)		(60,495)
Issuance of Voting Common Stock				232						232
Issuance of Non-Voting Common Stock:
On exercise of stock options			3	22,056	(531)					21,528
Under employee stock purchase plans				1,610						1,610
Under employee stock purchase incentive plan				2,710						2,710
Under restricted stock plan, net of forfeitures			6							6
Stock-based compensation				36,607						36,607
Tax benefit of stock option exercises				1,714						1,714
Repurchase of Voting Common Stock				(77)						(77)
Repurchase of Non-Voting Common Stock	144,071		(17)	(63,737)				(80,317)		(144,071)
Principal repayments on notes receivable from stock option exercises					1,283					1,283
Net subscriptions (redemptions/distributions) of non-controlling interest holders									(1,767)	(1,767)	(434)
Net consolidations (deconsolidations) of sponsored investment funds											(698)
Reclass to temporary equity									(119)	(119)	119
Purchase of non-controlling interests											(6,202)
Other changes in non-controlling interests				(1,115)						(1,115)	1,115
Ending balance, at Apr. 30, 2016		2	443	0	(10,391)	(40,856)	$ 7,363	657,386	1,702	615,649	87,583
Beginning balance, at Oct. 31, 2016	704,575	2	444	0	(12,074)	(57,583)		773,000	786	704,575	109,028
Net income	141,974							132,686	1,837	134,523	7,451
Other comprehensive income (loss)	(2,481)					(2,481)				(2,481)
Dividends declared								(64,559)		(64,559)
Issuance of Non-Voting Common Stock:
On exercise of stock options			6	41,873	(771)					41,108
Under employee stock purchase plans				1,516						1,516
Under employee stock purchase incentive plan				2,791						2,791
Under restricted stock plan, net of forfeitures			6							6
Stock-based compensation				39,214						39,214
Tax benefit of stock option exercises				7,183						7,183
Repurchase of Non-Voting Common Stock	78,984		(7)	(78,977)						(78,984)
Principal repayments on notes receivable from stock option exercises					2,660					2,660
Net subscriptions (redemptions/distributions) of non-controlling interest holders									(1,797)	(1,797)	90,509
Net consolidations (deconsolidations) of sponsored investment funds											(488)
Reclass to temporary equity									(64)	(64)	64
Purchase of non-controlling interests											(7,310)
Other changes in non-controlling interests				(860)						(860)	860
Ending balance, at Apr. 30, 2017	$ 788,490	$ 2	$ 449	16,399	$ (10,185)	$ (60,064)		$ 841,127	$ 762	788,490	$ 200,114
Issuance of Non-Voting Common Stock:
Tax benefit of non-controlling interest repurchases				$ 3,659						$ 3,659