Lease Cost and Other Information (Details) $ in Millions	3 Months Ended
	Jul. 31, 2019 USD ($)
Leases [Abstract]
Total lease cost	$ 5	[1]
Cash paid for amounts included in the measurement of lease liabilities	5	[2]
Right-of-use assets obtained in exchange for new lease liabilities	$ 3

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

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