Lease Cost and Other Information (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
		Jan. 31, 2020	Jan. 31, 2020
Leases [Abstract]
Total lease cost	[1]	$ 8	$ 21
Cash paid for amounts included in the measurement of lease liabilities	[2]	5	16
Right-of-use assets obtained in exchange for new lease liabilities		$ 3	$ 19

[1] Consists primarily of operating lease cost. Other components of lease cost were not material.

[2] Classified within operating activities in the accompanying condensed consolidated statement of cash flows.