Segments - Schedule of Company Derives Revenues (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2025	Apr. 30, 2024	Apr. 30, 2023
Segment Reporting Information [Line Items]
Total revenue	$ 2,761,086	$ 2,795,505	$ 2,863,836
Fee revenue
Segment Reporting Information [Line Items]
Total revenue	2,730,088	2,762,671	2,835,408
Fee revenue | U.S.
Segment Reporting Information [Line Items]
Total revenue	1,448,174	1,507,819	1,568,119
Fee revenue | United Kingdom
Segment Reporting Information [Line Items]
Total revenue	327,036	262,268	255,797
Fee revenue | Other countries
Segment Reporting Information [Line Items]
Total revenue	$ 954,878	$ 992,584	$ 1,011,492