Income Taxes - Components of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Apr. 25, 2020	Apr. 27, 2019
Deferred tax assets:
Capital accumulation plan	$ 2,541	$ 3,988
Inventory related items	10,354	4,887
Bad debt allowance	1,857	1,888
Stock based compensation expense	7,486	6,918
Interest rate swap	1,580	4,041
Foreign tax credit	7,248	7,358
Lease liability	16,572	0
Other	2,945	5,053
Gross deferred tax assets	50,583	34,133
Less: Valuation allowance	(14,886)	(11,237)
Total net deferred tax assets	35,697	22,896
Deferred tax liabilities
LIFO reserve	(32,630)	(24,098)
Amortizable intangibles	(69,254)	(77,126)
Goodwill	(11,848)	(43,903)
Property, plant, equipment	(39,999)	(40,793)
Lease, right-of-use asset	16,195	0
Total deferred tax liabilities	(169,926)	(185,920)
Deferred net long-term income tax liability	$ (134,229)	$ (163,024)