Common Stock Rollforward of Issued Shares (Details) - shares		12 Months Ended
	May 24, 2017	Apr. 30, 2018	Apr. 30, 2017
Class of Stock [Line Items]
Beginning balance		454,626,000	227,313,000
Retirement of treasury stock		(67,000,000)
Stock split		96,906,000	227,313,000
Ending balance		484,532,000	454,626,000
Common stock, Class A, voting [Member]
Class of Stock [Line Items]
Beginning balance		170,000,000	85,000,000
Retirement of treasury stock		0
Stock split		0	85,000,000
Ending balance		170,000,000	170,000,000
Common Stock, Class B, nonvoting [Member]
Class of Stock [Line Items]
Beginning balance		284,626,000	142,313,000
Retirement of treasury stock	(67,000,000)	(67,000,000)
Stock split		96,906,000	142,313,000
Ending balance		314,532,000	284,626,000