CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jul. 31, 2020	Apr. 30, 2020	Jul. 31, 2019
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 67,636	$ 64,648	$ 66,652
Accumulated depreciation and amortization	$ 817,280	$ 796,192	$ 764,891
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)	228,206,684	228,206,684	236,744,360
Treasury stock, shares (in shares)	35,308,213	35,731,376	35,785,391