Investments (Details) (USD $)	3 Months Ended		12 Months Ended
	Jul. 28, 2012	Jul. 30, 2011	Apr. 28, 2012
Schedule of Investments [Line Items]
Amount of investment which enhance return on cash	$ 7,800,000
Gross Unrealized Gains	2,466,000		2,908,000
Gross Unrealized Losses	(129,000)		(90,000)
Fair Value	18,582,000		11,200,000
Sales of Available-for-sale Securities [Abstract]
Proceeds from sales	1,428,000	2,160,000
Gross realized gains	224,000	395,000
Gross realized losses	(26,000)	(3,000)
Other Long-Term Assets [Member]
Schedule of Investments [Line Items]
Available-for-sale investments	15,000,000		10,200,000
Trading securities			1,000,000
Other Current Assets [Member]
Schedule of Investments [Line Items]
Available-for-sale investments	3,600,000
Equity securities [Member]
Schedule of Investments [Line Items]
Gross Unrealized Gains	2,348,000		2,806,000
Gross Unrealized Losses	(108,000)		(83,000)
Fair Value	6,428,000		7,237,000
Fixed income [Member]
Schedule of Investments [Line Items]
Gross Unrealized Gains	118,000		102,000
Gross Unrealized Losses	(21,000)		(7,000)
Fair Value	10,992,000		2,850,000
Available-for-sale fair value by contractual maturity [Abstract]
Available-for-sale securities, after one through five years, fair value	3,600,000
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	5,900,000
Available-for-sale securities, after five through ten years, fair value	1,000,000
Available-for-sale securities, after ten years, fair value	500,000
Mutual funds [Member]
Schedule of Investments [Line Items]
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Fair Value	1,000,000		950,000
Other [Member]
Schedule of Investments [Line Items]
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Fair Value	$ 162,000		$ 163,000