Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Apr. 30, 2016	May 02, 2015	May 03, 2014
Tax Credit Carryforward [Line Items]
Unrecognized tax benefits attributable to book to tax differences in share-based compensation	$ 6,700,000
Deferred tax benefit related to release of foreign valuation allowance	(2,700,000)	$ 6,300,000	$ (2,500,000)
Valuation allowance	1,300,000	2,000,000
Federal income tax benefit	700,000
State income tax benefit	3,700,000
Foreign tax credit carryforward	900,000	3,700,000
Income taxes paid	10,000,000	9,000,000	$ 6,200,000
Tax provision on undistributed net income of foreign operations	0
Undistributed foreign earnings	350,800,000
Approximate additional income tax expense if undistributed earnings were distributed	122,800,000
Unrecognized tax benefits	1,200,000	$ 900,000
Accrued for interest on income tax matters	100,000
Accrued for penalties on income tax matters	0
Federal
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	2,100,000
State
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	$ 85,800,000
Foreign tax authority | Investment tax credit | Malta
Tax Credit Carryforward [Line Items]
Percentage of qualified expenditures subject to investment tax credit	30.00%
Amount of unused credits	$ 14,400,000
Federal and state operating loss carryforwards
Tax Credit Carryforward [Line Items]
Valuation allowance	$ 1,300,000