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Stockholders' Equity - Reconciliation of Retained Earnings (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 27, 2017	Jan. 29, 2016	Jan. 27, 2017	Jan. 29, 2016
Retained Earnings Adjustments [Line Items]
Beginning balance			$ 0
Cumulative-effect of new accounting principle			21
Net income	$ 146	$ 153	319	$ 237
Repurchases of common stock			(576)
Ending balance	$ 0		0
Retained Earnings
Retained Earnings Adjustments [Line Items]
Repurchases of common stock			(271)
Dividends			$ (69)