Available-For-Sale Securities (Schedule Of Available-For-Sale Securities Classified As Current Assets) (Details) (USD $) In Thousands, unless otherwise specified	Aug. 30, 2014		May 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Investment securities available-for-sale	$ 197,908		$ 196,189
Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	196,218		194,434
Gains in Accumulated Other Comprehensive Income	209		304
Investment securities available-for-sale	196,427		194,738
Noncurrent Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	952		999
Gains in Accumulated Other Comprehensive Income	529		452
Investment securities available-for-sale	1,481		1,451
State Municipal Bonds [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	73,363		75,659
Gains in Accumulated Other Comprehensive Income	201		188
Investment securities available-for-sale	73,564		75,847
US Government Obligations [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,755		4,056
Gains in Accumulated Other Comprehensive Income	2		5
Investment securities available-for-sale	3,757		4,061
Corporate Bonds [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	107,327		102,587
Gains in Accumulated Other Comprehensive Income	1		98
Investment securities available-for-sale	107,328		102,685
Commercial Paper [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,246		3,927
Gains in Accumulated Other Comprehensive Income			3
Investment securities available-for-sale	3,246		3,930
Certificates Of Deposit [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	250		350
Gains in Accumulated Other Comprehensive Income			1
Investment securities available-for-sale	250		351
Foreign Government Obligations [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,059		1,064
Gains in Accumulated Other Comprehensive Income	1		2
Investment securities available-for-sale	1,060		1,066
Government Agency Bonds [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,218		4,791
Gains in Accumulated Other Comprehensive Income	4		7
Investment securities available-for-sale	4,222		4,798
Variable Rate Demand Notes [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,000		2,000
Investment securities available-for-sale	3,000		2,000
Mutual Funds [Member] | Noncurrent Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	952	[1]	999	[1]
Gains in Accumulated Other Comprehensive Income	529	[1]	452	[1]
Investment securities available-for-sale	$ 1,481	[1]	$ 1,451	[1]

[1] The mutual funds are classified as long term and are a part of “other investments” in the Condensed Consolidated Balance Sheet.