Income Taxes - Components of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Apr. 27, 2019	Apr. 28, 2018
Deferred tax assets:
Capital accumulation plan	$ 3,988	$ 4,862
Inventory related items	4,887	4,407
Bad debt allowance	1,888	1,052
Stock based compensation expense	6,918	6,514
Interest rate swap	4,041	4,712
Foreign tax credit	7,358	8,472
Other	5,053	11,748
Gross deferred tax assets	34,133	41,767
Less: Valuation allowance	(11,237)	(13,830)
Total net deferred tax assets	22,896	27,937
Deferred tax liabilities
LIFO reserve	(24,098)	(19,727)
Amortizable intangibles	(77,126)	(84,778)
Goodwill	(43,903)	(41,635)
Property, plant, equipment	(40,793)	(33,376)
Total deferred tax liabilities	(185,920)	(179,516)
Deferred net long-term income tax liability	$ (163,024)	$ (151,579)