Fee Revenue - Schedule of Disaggregation of Fee Revenue by Industry (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2020	Jul. 31, 2019
Disaggregation Of Revenue [Line Items]
Fee Revenue	$ 346,883	$ 496,198
Industrial
Disaggregation Of Revenue [Line Items]
Fee Revenue	$ 95,311	$ 138,312
Fee Revenue, Percentage	27.70%	28.50%
Financial Services
Disaggregation Of Revenue [Line Items]
Fee Revenue	$ 65,727	$ 86,212
Fee Revenue, Percentage	19.10%	17.80%
Life Sciences/Healthcare
Disaggregation Of Revenue [Line Items]
Fee Revenue	$ 65,450	$ 82,265
Fee Revenue, Percentage	19.00%	17.00%
Consumer Goods
Disaggregation Of Revenue [Line Items]
Fee Revenue	$ 44,778	$ 71,698
Fee Revenue, Percentage	13.00%	14.80%
Technology
Disaggregation Of Revenue [Line Items]
Fee Revenue	$ 49,324	$ 70,803
Fee Revenue, Percentage	14.40%	14.60%
Education/Non-Profit/General
Disaggregation Of Revenue [Line Items]
Fee Revenue	$ 23,507	$ 35,259
Fee Revenue, Percentage	6.80%	7.30%
Fee Revenue
Disaggregation Of Revenue [Line Items]
Fee Revenue	$ 344,097	$ 484,549
Fee Revenue, Percentage	100.00%	100.00%