Employee Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 26, 2017	Aug. 27, 2016	Aug. 29, 2015
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 271	$ 204	$ 192
Interest cost	244	307	294
Expected return on assets	(189)	(177)	(182)
Amortization of prior service cost	83	84	62
Amortization of unrecognized loss	149	105	152
Other events	125	43	174
Net periodic benefit cost	683	566	692
SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	785	819	821
Interest cost	1,003	984	1,133
Expected return on assets	0	0	0
Amortization of prior service cost	56	368	368
Amortization of unrecognized loss	653	274	461
Other events	0	0	0
Net periodic benefit cost	$ 2,497	$ 2,445	$ 2,783