Employee Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2019	Aug. 25, 2018	Aug. 26, 2017
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 114	$ 115	$ 271
Interest cost	260	257	244
Expected return on assets	(199)	(174)	(189)
Amortization of prior service cost	66	66	83
Amortization of unrecognized loss	51	102	149
Other events	503	96	125
Net periodic benefit cost	795	462	683
SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	725	694	785
Interest cost	1,148	1,027	1,003
Expected return on assets	0	0	0
Amortization of prior service cost	0	0	56
Amortization of unrecognized loss	247	362	653
Other events	0	0	0
Net periodic benefit cost	$ 2,120	$ 2,083	$ 2,497