Note 6 - Stockholders' Equity - Stock-based Compensation Activity (Details) - $ / shares	12 Months Ended
	May 28, 2017	May 29, 2016	May 31, 2015
Balance (in shares)	465,968	881,143	2,000,000
Balance (in dollars per share)		$ 14.02
Granted (in shares)	(370,522)	(443,175)	(1,118,857)
Forfeited (in shares)		28,000
Forfeited (in shares)	59,793
Forfeited (in shares)		(28,000)
Balance (in dollars per share)	$ 13.58		$ 14.02
Balance (in shares)	155,239	465,968	881,143
Restricted Stock [Member]
Balance (in shares)	526,841	392,771	149,300
Balance (in dollars per share)	$ 13.51	$ 14.15	$ 13.17
Granted (in shares)	130,522	177,675	324,357
Granted (in dollars per share)	$ 13.37	$ 12.10	$ 13.97
Granted (in dollars per share)	$ 13.37	$ 12.10	$ 13.97
Awarded/Exercised (in shares)	(130,508)	(32,439)	(79,219)
Awarded/Exercised (in dollars per share)	$ 13.42	$ 13.28	$ 11.57
Forfeited (in shares)	17,500	11,166	1,667
Forfeited (in shares)	(17,500)	(11,166)	(1,667)
Forfeited (in dollars per share)	$ 12.46	$ 14.36	$ 14.30
Balance (in dollars per share)	$ 13.53	$ 13.51	$ 14.15
Balance (in shares)	509,355	526,841	392,771
Employee Stock Option [Member]
Balance (in shares)	1,731,474	1,736,718	1,215,860
Balance (in dollars per share)	$ 11.90	$ 11.19	$ 8.45
Granted (in shares)	240,000	265,500	794,500
Granted (in dollars per share)	$ 11.58	$ 12.04	$ 14.20
Awarded/Exercised (in shares)	(357,639)	(220,717)	(205,419)
Awarded/Exercised (in dollars per share)	$ 5.93	$ 6.44	$ 6.55
Forfeited (in shares)	(42,293)	(24,473)	(2,223)
Forfeited (in dollars per share)	$ 12.16	$ 14.38	$ 14.30
Plan shares expired (in shares)		(25,554)	(66,000)
Balance (in shares)	1,571,542	1,731,474	1,736,718
Balance (in dollars per share)	$ 13.20	$ 11.90	$ 11.19
Plan shares expired (in dollars per share)		$ 9.86	$ 11.32