Acquisitions, Goodwill and Intangible Assets (Narrative) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2016	Dec. 21, 2018	Oct. 31, 2014	Oct. 31, 2013
Business Acquisition [Line Items]
Goodwill impairment			$ 0	$ 0	$ 0
Amortizing intangible assets amortization expense			8,900,000	9,000,000	8,600,000
Impairment of amortizing or non-amortizing intangible assets			0	$ 0	$ 0
Atlanta Capital [Member]
Business Acquisition [Line Items]
Non-controlling interest holders total (direct and indirect) profits interest, end of period				11.60%		9.80%
Purchase of non-controlling interests				$ 3,200,000
Payments for repurchase of redeemable noncontrolling interests	$ 2,500,000	$ 700,000
Amount paid for indirect profit interest pursuant to the put and call provisions of the Long-term Equity Incentive Plan			$ 8,200,000	4,200,000
Estimated fair value of noncontrolling interests				$ 27,300,000		$ 26,300,000
Parametric Portfolio Associates [Member]
Business Acquisition [Line Items]
Non-controlling interest holders total (direct and indirect) profits interest, end of period				6.00%		5.10%
Parametric Portfolio Associates [Member] | Eaton Vance [Member]
Business Acquisition [Line Items]
Non-controlling interest holders capital ownership percentage, end of period				1.30%		0.80%
Parametric Portfolio Associates [Member] | Parametric Risk Advisors [Member]
Business Acquisition [Line Items]
Estimated fair value of noncontrolling interests				$ 14,700,000		$ 15,900,000
Noncontrolling capital and profits interest issued in acquisition							20.00%
Noncontolling indirect profit interest acquired duing the exchange by Parametric and issued to employees							0.80%
Noncontrolling indirect capital interest acquired during the exchange by Parametric and issued to employees							0.80%
Redeemable noncontrolling interest, exercise term			4 years
Parametric Portfolio Associates [Member] | Clifton Group [Member]
Business Acquisition [Line Items]
Company's increase in capital interest percentage under acquisition agreement, during the period			0.50%
Company's increase in profit interest percentage under acquisition agreement, during the period			0.50%
Purchase of non-controlling interests			$ 8,400,000	$ 6,900,000
Noncontolling indirect profit interest acquired duing the exchange by Parametric and issued to employees								1.90%
Noncontrolling indirect capital interest acquired during the exchange by Parametric and issued to employees								1.90%
Parametric Portfolio Associates [Member] | Parametric Plan [Member]
Business Acquisition [Line Items]
Non-controlling interest holders total (direct and indirect) profits interest, end of period			4.30%	4.70%
Amount paid for indirect profit interest pursuant to the put and call provisions of the Long-term Equity Incentive Plan			$ 5,900,000	$ 5,700,000
Estimated fair value of noncontrolling interests			$ 47,900,000	46,300,000
Tax Advantaged Bond Strategies [Member]
Business Acquisition [Line Items]
Goodwill, Acquired During Period				$ 11,600,000