Lease Cost and Other Information (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
		Oct. 31, 2019	Oct. 31, 2019
Leases [Abstract]
Total lease cost	[1]	$ 6	$ 11
Cash paid for amounts included in the measurement of lease liabilities	[2]	6	11
Right-of-use assets obtained in exchange for new lease liabilities		$ 13	$ 16

[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.