Note 7 - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 27, 2016	Aug. 29, 2015	Aug. 30, 2014
Pension Plan [Member]
Service cost	$ 204	$ 192	$ 172
Interest cost	307	294	328
Expected return on assets	(177)	(182)	(183)
Amortization of prior service cost	84	62	62
Amortization of unrecognized loss	105	152	113
Other events	43	174	72
Net periodic benefit cost	566	692	564
Supplemental Executive Retirement Plan [Member]
Service cost	819	821	615
Interest cost	984	1,133	942
Expected return on assets
Amortization of prior service cost	368	368	368
Amortization of unrecognized loss	274	461	151
Other events
Net periodic benefit cost	$ 2,445	$ 2,783	$ 2,076