Variable Interest Entities Investments in VIEs That Are Consolidated (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jan. 31, 2018	Oct. 31, 2017
Assets:
Cash	$ 454	$ 0
Bank loan investments	76,554	31,348
Other assets	5,183	0
Liabilities:
Other liabilities	25,283	0
Liabilities:
Line of credit	36,534	12,598
Eaton Vance CLO 2017-1 [Member]
Investments In Variable Interest Entities That Are Consolidated Details [Line Items]
The Company's contribution to a CLO entity		18,800
CLO line of credit, maximum borrowing capacity		160,000
CLO line of credit, amount outstanding	$ 36,500	$ 12,600
Date on which the CLO entity was consolidated		Aug. 24, 2017
CLO line of credit, description	The size of the non-recourse revolving line of credit can be increased subject to the occurrence of certain events and the mutual consent of the parties. The line of credit is secured by all of the commercial bank loan investments in CLO 2017-1 and initially bears interest at a rate of daily LIBOR plus 1.25 percent per annum (with such interest rate, upon completion of the initial twelve-month warehousing period, increasing to daily LIBOR plus 2.0 percent per annum). The third-party lender does not have any recourse to the Company’s general credit.
Unpaid principal balance (Total CLO bank loan investments)	$ 75,660
Unpaid principal balance over fair value (Total CLO bank loan investments)	894
Fair Value (Total CLO bank loan investments)	76,554
Unpaid principal balance (90 days or more past due)	0
Unpaid principal balance over fair value (90 days or more past due)	0
Fair Value (90 days or more past due)	0
Net gains (losses) resulting from change in fair value of the CLO entity's bank loans and other investments	900
Net income (losses) attributable to Eaton Vance Corp. shareholders related to the consolidated CLO entity	$ 1,600
Eaton Vance CLO 2015-1 [Member]
Liabilities:
Date of equity interest purchase in CLO entity	Nov. 01, 2017
Percentage of equity interest purchased in CLO entity	100.00%
Amount paid to acquire equity interest in CLO entity	$ 26,700
Trade date of sale of equity interest in CLO entity	Dec. 08, 2017
Settlement date of sale of equity interest in CLO entity	Dec. 22, 2017
Percentage of equity interest in CLO entity sold	95.00%
Proceeds from sale of equity interest in CLO entity	$ 24,700
Loss on disposal of equity interest in CLO entity	$ 600
The Company's remaining equity interest ownership percent	5.00%
Senior debt tranches of the CLO entity held by the Company	$ 18,900
The Company's total investment in the CLO entity	$ 20,300