Income Taxes - Components of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Apr. 29, 2017	Apr. 30, 2016
Deferred tax assets:
Capital accumulation plan	$ 7,676	$ 5,898
Inventory related items	6,236	6,776
Bad debt allowance	2,317	2,649
Stock based compensation expense	8,663	9,985
Interest rate swap	8,656	9,749
Foreign tax credit	8,917	9,300
Net operating loss carryforwards	0	363
Other	14,269	11,979
Gross deferred tax assets	56,734	56,699
Less: Valuation allowance	(14,053)	(14,007)
Total net deferred tax assets	42,681	42,692
Deferred tax liabilities
LIFO reserve	(25,833)	(21,294)
Amortizable intangibles	(133,037)	(156,782)
Goodwill	(61,108)	(57,405)
Property, plant, equipment	(14,389)	(11,748)
Total deferred tax liabilities	(234,367)	(247,229)
Deferred net long-term income tax liability	$ (191,686)	$ (204,537)