Accounting Policies - Inventories (Details)	Apr. 27, 2019	Apr. 28, 2018
Inventories
Inventory cost determined using LIFO basis (as a percent)	62.00%	64.00%

The percentage of LIFO (last in first out) inventory to total inventory as of the balance sheet date if other than 100 percent.

No definition available.

Name:	us-gaap_PercentageOfLIFOInventory
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant