Non-operating income (expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Non-operating income (expense)
Interest and other income	$ 5,958	$ 4,186	$ 10,601	$ 5,361
Net gains (losses) on investments and derivatives	3,483	789	(453)	1,374
Net foreign currency losses	(153)	(1,186)	(366)	(106)
Gains and other investment income, net	9,288	3,789	9,782	6,629
Interest expense	(8,065)	(7,340)	(15,412)	(14,682)
Other income (expense) of consolidated collateralized loan obligation (CLO) entity:
Interest income	0	4,850	0	8,593
Net gains on bank loans, other investments and note obligations	0	9,058	0	8,594
Gains and other investment income, net	0	13,908	0	17,187
Interest expense	0	(2,878)	0	(4,714)
Total non-operating income (expense)	$ 1,223	$ 7,479	$ (5,630)	$ 4,420