Income Taxes - Components of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Apr. 30, 2016	Apr. 25, 2015
Deferred tax assets:
Capital accumulation plan	$ 5,898	$ 5,723
Inventory related items	6,776	4,484
Bad debt allowance	2,649	1,380
Stock based compensation expense	9,985	7,995
Interest rate swap	9,749	10,872
Foreign tax credit	9,300	0
Net operating loss carryforwards	363	0
Other	11,979	8,390
Gross deferred tax assets	56,699	38,844
Less: Valuation allowance	(14,007)	0
Total net deferred tax assets	42,692	38,844
Deferred tax liabilities
LIFO reserve	(21,294)	(19,173)
Amortizable intangibles	(156,782)	(2,310)
Goodwill	(57,405)	(52,140)
Property, plant, equipment	(11,748)	(4,695)
Total deferred tax liabilities	(247,229)	(78,318)
Deferred net long-term income tax liability	$ (204,537)	$ (39,474)