Statements of Cash Flows Additional Information - Supplemental Cash Flows and Non Cash Investing Activities (Detail) - USD ($) $ in Millions	9 Months Ended
	Jan. 29, 2016	Jan. 23, 2015
Non-cash Investing Activities:
Capital expenditures incurred but not paid	$ 14	$ 12
Acquisition of software through long-term financing	0	12
Supplemental Cash Flow Information:
Income taxes paid, net of refunds	113	89
Interest paid	$ 40	$ 33