Employee Benefit Plans - Obligations and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2019	Aug. 25, 2018	Aug. 26, 2017
Pension Plans
Change in benefit obligation:
Projected benefit obligation, beginning of year	$ 7,449	$ 8,382
Service cost	114	115	$ 271
Interest cost	260	257	244
Actuarial loss (gain)	163	(673)
Benefits paid	(50)	(84)
Settlements	(2,370)	(548)
Projected benefit obligation, end of year	5,566	7,449	8,382
Change in plan assets:
Fair value of plan assets, beginning of year	6,325	5,097
Actual return on plan assets	170	72
Employer contributions	528	1,788
Benefits paid	(50)	(84)
Settlements	(2,370)	(548)
Fair value of plan assets, end of year	4,603	6,325	5,097
Funded status (net amount recognized):	(963)	(1,124)
SERP
Change in benefit obligation:
Projected benefit obligation, beginning of year	27,547	28,801
Service cost	725	694	785
Interest cost	1,148	1,027	1,003
Actuarial loss (gain)	7,456	(2,129)
Benefits paid	(909)	(846)
Settlements	0	0
Projected benefit obligation, end of year	35,967	27,547	28,801
Change in plan assets:
Fair value of plan assets, beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	0	0
Benefits paid	0	0
Settlements	0	0
Fair value of plan assets, end of year	0	0	$ 0
Funded status (net amount recognized):	$ (35,967)	$ (27,547)