Consolidated Statements of Cash Flows	12 Months Ended
	Oct. 31, 2018 USD ($)		Oct. 31, 2017 USD ($)		Oct. 31, 2016 USD ($)
Cash Flows From Operating Activities:
Net income	$ 397,905,000		$ 306,373,000		$ 264,757,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	25,013,000		19,132,000		20,798,000
Unamortized loss on derivative instrument	0		(684,000)		0
Amortization of deferred sales commissions	18,394,000		16,231,000		15,458,000
Stock-based compensation	87,047,000		79,525,000		71,337,000
Deferred income taxes	25,246,000		14,345,000		22,089,000
Net losses on investments and derivatives	17,796,000		1,900,000		116,000
Loss on expiration of Hexavest option	6,523,000		0		0
Equity in net income of affiliates, net of tax	(11,373,000)		(10,870,000)		(10,552,000)
Dividends received from affiliates	12,243,000		11,447,000		11,460,000
Loss on extinguishment of debt	0		5,396,000		0
Consolidated CLO entities' operating activities:
Net gains on bank loan, other investments and note obligations	(1,999,000)		0		(6,094,000)
Amortization	(248,000)		0		(624,000)
(Increase) decrease in other assets and cash, net of other liabilities	(165,470,000)		0		80,468,000
Changes in operating assets and liabilities:
Management fees and other receivables	(36,427,000)		(14,167,000)		1,334,000
Investments in trading securities	(245,054,000)		(396,619,000)		(93,420,000)
Deferred sales commissions	(30,598,000)		(25,577,000)		(17,380,000)
Other assets	(7,727,000)		(11,608,000)		(4,051,000)
Accrued compensation	26,806,000		33,489,000		(4,845,000)
Accounts payable and accrued expenses	10,287,000		7,330,000		(5,482,000)
Other liabilities	5,286,000		44,032,000		(1,889,000)
Net cash provided by operating activities	133,650,000		79,675,000		343,480,000
Cash Flows From Investing Activities:
Additions to equipment and leasehold improvements	(18,747,000)		(12,698,000)		(10,682,000)
Issuance of loan to affiliate	0		0		(5,000,000)
Net cash paid in acquisition	0		(63,605,000)		(10,155,000)
Proceeds from sale of investments	24,486,000	[1]	16,502,000	[1]	12,707,000	[1]
Purchase of investments	(7,022,000)	[1]	(276,000)	[1]	(17,177,000)	[1]
Proceeds from sale of investments in CLO entity note obligations	76,563,000	[1]	0	[1]	4,668,000	[1]
Purchase of investments in CLO entity note obligations	(147,322,000)	[1]	0	[1]	0	[1]
Consolidated CLO entities' investing activities:
Proceeds from sales of bank loans and other investments	154,871,000		0		166,460,000
Purchase of bank loans and other investments	(407,883,000)		(31,348,000)		(249,099,000)
Net cash used for investing activities	(325,054,000)		(91,425,000)		(108,278,000)
Cash Flows From Financing Activities:
Purchase of additional non-controlling interest	(20,818,000)		(9,820,000)		(15,673,000)
Debt issuance costs	0		(2,761,000)		0
Proceeds from issuance of debt	0		298,896,000		0
Repayment of debt	0		(250,000,000)		0
Loss on extinguishment of debt	0		(5,396,000)		0
Principal repayments on notes receivable from stock option exercises	4,825,000		4,500,000		3,257,000
Dividends paid	(144,855,000)		(125,785,000)		(118,621,000)
Net subscriptions received from (redemptions/distributions paid to) non-controlling interest holders	100,360,000		188,463,000		302,000
Consolidated CLO entities' financing activities:
Proceeds from line of credit	245,898,000		12,598,000		0
Repayment of line of credit	(258,496,000)		0		0
Issuance of senior and subordinated note obligations	1,320,397,000		0		0
Principal repayments of senior and subordinated note obligations	(865,624,000)		0		0
Net cash provided by (used for) financing activities	184,413,000		195,430,000		(273,130,000)
Effect of currency rate changes on cash and cash equivalents	(2,868,000)		2,701,000		(3,456,000)
Net increase (decrease) in cash and cash equivalents	(9,859,000)		186,381,000		(41,384,000)
Cash and cash equivalents, beginning of year	610,555,000		424,174,000		465,558,000
Cash and cash equivalents, end of year	600,696,000		610,555,000		424,174,000
Supplemental Cash Flow Information:
Cash paid for interest	22,660,000		25,535,000		28,413,000
Cash paid for interest upon repayment of debt	0		1,354,000		0
Cash paid for interest by consolidated CLO entities	10,681,000		0		11,024,000
Cash paid for income taxes, net of refunds	135,105,000		143,948,000		128,845,000
Supplemental Disclosure of Non-Cash Information:
Increase in equipment and leasehold improvements due to non-cash additions	1,336,000		863,000		453,000
Exercise of stock options through issuance of notes receivable	1,770,000		3,538,000		4,188,000
Non-controlling interest call option exercises recorded in other liabilities	14,133,000		12,379,000		2,510,000
Increase (decrease) in non-controlling interest due to net consolidation (deconsolidation) of sponsored investment funds	(25,320,000)		129,587,000		(1,567,000)
Increase in bank loans and other investments of consolidated CLO entities due to unsettled purchases	149,617,000		0		0
Initial Consolidation of CLO Entities:
Increase in bank loans and other investments	814,122,000		31,348,000		0
Increase in senior loan obligations	843,089,000		0		0
Increase in line of credit	0		12,598,000		0
Deconsolidation of CLO Entities:
Decrease in bank loans and other investments	379,676,000		0		(389,856,000)
Decrease in senior and subordinated loan obligations	378,742,000		0		(397,544,000)
Voting Common Stock [Member]
Cash Flows From Financing Activities:
Proceeds From Issuance Of Voting Common Stock	0		0		232,000
Repurchase of Common Stock	(171,000)		0		(77,000)
Non-Voting Common Stock [Member]
Cash Flows From Financing Activities:
Proceeds from issuance of Non-Voting Common Stock	76,447,000		210,934,000		110,425,000
Repurchase of Common Stock	(273,550,000)		(126,199,000)		(252,975,000)
Supplemental Disclosure of Non-Cash Information:
Non-Voting Common Stock repurchases recorded in accounts payable and accrued expenses	$ 13,136,000		$ 0		$ 0

[1] In fiscal 2018, the Company elected to present the investing cash flows related to the purchase and sale of investments in CLO entity note obligations separately from the purchase and sale of other investments. The prior year amounts, which were previously presented within the purchase and sale of investments line items, were reclassified to these line items for comparability purposes.