CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Oct. 31, 2020	Apr. 30, 2020	Oct. 31, 2019
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 66,808	$ 64,648	$ 65,815
Accumulated depreciation and amortization	$ 832,080	$ 796,192	$ 784,535
Common stock, stated value per share (in usd per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	800,000,000	800,000,000	800,000,000
Common stock, shares issued (in shares)	218,719,439	228,206,684	231,024,069
Treasury stock, shares (in shares)	35,301,097	35,731,376	35,778,404