Share-Based Payments (Details 3) - $ / shares	12 Months Ended
	Apr. 30, 2022	Apr. 30, 2021	Apr. 30, 2020
Restricted Shares And Deferred Stock Units [Member]
Weighted-average grant date fair values of the equity awards
Restricted Shares and Deferred Stock Units and Performance Units	66,514	83,188	245,945
Weighted-Average Grant Date Fair Value Per Share	$ 135.10	$ 110.66	$ 121.19
Performance Units [Member]
Weighted-average grant date fair values of the equity awards
Restricted Shares and Deferred Stock Units and Performance Units	171,907	194,786	168,212
Weighted-Average Grant Date Fair Value Per Share	$ 135.53	$ 113.70	$ 123.68