Available-For-Sale Securities (Schedule Of Available-For-Sale Securities Classified As Current Assets) (Details) (USD $) In Thousands, unless otherwise specified	Nov. 29, 2014		May 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Investment securities available-for-sale	$ 192,984		$ 196,189
Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	191,362		194,434
Gains in Accumulated Other Comprehensive Income	191		304
Losses in Accumulated Other Comprehensive Income	19
Investment securities available-for-sale	191,534		194,738
Noncurrent Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	942		999
Gains in Accumulated Other Comprehensive Income	508		452
Investment securities available-for-sale	1,450		1,451
State Municipal Bonds [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	74,779		75,659
Gains in Accumulated Other Comprehensive Income	175		188
Investment securities available-for-sale	74,954		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	10		5
Investment securities available-for-sale	3,765		4,061
Corporate Bonds [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	103,641		102,587
Gains in Accumulated Other Comprehensive Income			98
Losses in Accumulated Other Comprehensive Income	19
Investment securities available-for-sale	103,622		102,685
Commercial Paper [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,496		3,927
Gains in Accumulated Other Comprehensive Income	1		3
Investment securities available-for-sale	2,497		3,930
Certificates Of Deposit [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost			350
Gains in Accumulated Other Comprehensive Income			1
Investment securities available-for-sale			351
Foreign Government Obligations [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,053		1,064
Gains in Accumulated Other Comprehensive Income	2		2
Investment securities available-for-sale	1,055		1,066
Government Agency Bonds [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,638		4,791
Gains in Accumulated Other Comprehensive Income	3		7
Investment securities available-for-sale	4,641		4,798
Variable Rate Demand Notes [Member] | Current Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,000		2,000
Investment securities available-for-sale	1,000		2,000
Mutual Funds [Member] | Noncurrent Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	942	[1]	999	[1]
Gains in Accumulated Other Comprehensive Income	508	[1]	452	[1]
Investment securities available-for-sale	$ 1,450	[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.