Variable Interest Entities Investments in VIEs That Are Consolidated (Details) - Eaton Vance CLO 2015-1 [Member] - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2016	Oct. 31, 2016
Investments In Variable Interest Entities That Are Consolidated Details [Line Items]
Residual interest percentage sold in the CLO			16.10%
Gain on disposal of interest in the subordinated obligation of CLO entity			$ 0.1
Date on which the CLO entity was deconsolidated			Sep. 21, 2016
Net gains (losses) resulting from change in fair value of the CLO entity's bank loans and other investments	$ 2.5	$ (4.5)
Net gains (losses) resulting from change in the fair value of the CLO note obligations	6.6	13.1
Combined consolidated CLO entity net gains (losses)	9.1	8.6
The third-party note holders of the CLO entities net income (loss) recorded during the period included in net income attributable to non-controlling and other beneficial interests	(10.8)	(12.7)
The CLO's net income (loss) recorded in the Company's Consolidated Statement of Income	11.0	12.4
Net income (losses) attributable to Eaton Vance Corp. shareholders related to the consolidated CLO entity	$ 0.2	$ (0.3)