Variable Interest Entities (Summary of Application of the Measurement Alternative Results in the Companys Earnings from Consolidated VIE Subsequent to Initial Consolidation) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2017
Economic interests in Consolidated Securitized CLO Entities [Abstract]
Revenue	$ 433,740	$ 431,235	$ 411,861	$ 406,416	$ 430,795	$ 428,691	$ 412,700	$ 420,236	$ 1,683,252	$ 1,692,422	$ 1,532,111
Equity in net income of affiliates, net of tax									9,090	11,373	$ 10,870
Consolidated Securitized CLO Entities [Member]
Economic interests in Consolidated Securitized CLO Entities [Abstract]
Distribution received and unrealized gains (losses) on the senior and subordinated interests held by the company									3,266	(2,319)
Revenue									5,838	787
Equity in net income of affiliates, net of tax									$ 9,104	$ (1,532)