Income Taxes - Deferred Income Taxes - Narrative (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 29, 2018	Apr. 30, 2017
Income Taxes [Line Items]
U.S. foreign income tax credits	$ 5,720	$ 44,917
U.S. foreign income tax credits, expiration period	10 years
U.S. Tax Authorities [Member]
Income Taxes [Line Items]
Operating loss carryforwards	$ 11,500
Operating loss carryforwards, related future tax benefits	$ 2,500
Earliest Tax Year [Member] | U.S. Tax Authorities [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration fiscal year	2027
Latest Tax Year [Member] | U.S. Tax Authorities [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration fiscal year	2035