Employee Benefit Plans (Details) (USD $)	12 Months Ended
	Aug. 27, 2011	Aug. 28, 2010	Aug. 29, 2009
Defined Benefit Plan Disclosure [Line Items]
Contributions charged to expense	$ 10,600,000	$ 11,000,000	$ 13,600,000
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions charged to expense	1,700,000	1,500,000	1,500,000
Components of net periodic benefit cost [Abstract]
Service cost	486,000	391,000
Interest cost	764,000	702,000
Expected return on assets	0	0	0
Amortization of prior service cost	368,000	368,000	368,000
Amortization of unrecognized loss	131,000	54,000	77,000
Other events	0	0	0
Net periodic benefit cost	1,749,000	1,515,000	1,452,000
Change in benefit obligation [Rollforward]
Project benefit obligation, beginning of year	13,987,000	11,925,000
Service cost	486,000	391,000
Interest cost	764,000	702,000
Actuarial (gain) loss	98,000	1,355,000
Benefits paid	(391,000)	(386,000)
Settlements	0	0
Project benefit obligation, end of year	14,944,000	13,987,000	11,925,000
Change in plan assets [Rollforward]
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
Fair value of plan assets, end of year	0	0	0
Funded status (net amount recognized):	(14,944,000)	(13,987,000)
Accumulated benefit obligations [Abstract]
Accumulated benefit obligations	11,600,000	10,900,000
Amounts recognized in balance sheet [Abstract]
Deferred tax assets	1,716,000	1,991,000
Accrued liabilities	14,944,000	13,987,000
Accumulated other comprehensive loss	(2,742,000)	(3,114,000)
Amounts recognized in other accumulated other comprehensive income (loss), before tax [Abstract]
Net actuarial loss	(1,577,000)	(1,734,000)
Unrecognized prior service cost	(1,165,000)	(1,380,000)
Total	(2,742,000)	(3,114,000)
Weighted average assumptions used in calculating benefit obligation [Abstract]
Discount rate (in hundredths)	4.90%	4.80%
Rate of compensation increase (in hundredths)	5.00%	5.00%
Defined benefit plan, weighted average assumptions used in calculating net periodic benefit cost [Abstract]
Discount rate (in hundredths)	4.80%	5.70%	6.00%
Expected return on plan assets (in hundredths)	0.00%	0.00%	0.00%
Rate of compensation increase (in hundredths)	5.00%	5.00%	5.00%
Unifirst Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions charged to expense	300,000	300,000	200,000
Textilease Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions charged to expense	100,000	100,000	100,000
Pension Plans, Defined Benefit [Member]
Components of net periodic benefit cost [Abstract]
Service cost	149,000	136,000
Interest cost	328,000	351,000
Expected return on assets	(202,000)	(191,000)	(243,000)
Amortization of prior service cost	62,000	62,000	62,000
Amortization of unrecognized loss	78,000	20,000	13,000
Other events	65,000	0	0
Net periodic benefit cost	480,000	378,000	313,000
Change in benefit obligation [Rollforward]
Project benefit obligation, beginning of year	7,339,000	6,205,000
Service cost	149,000	136,000
Interest cost	328,000	351,000
Actuarial (gain) loss	114,000	921,000
Benefits paid	(319,000)	(274,000)
Settlements	(239,000)	0
Project benefit obligation, end of year	7,372,000	7,339,000	6,205,000
Change in plan assets [Rollforward]
Fair value of plan assets, beginning of year	5,263,000	5,050,000
Actual return on plan assets	205,000	331,000
Employer contributions	235,000	156,000
Benefits paid	(319,000)	(274,000)
Settlements	(239,000)	0
Fair value of plan assets, end of year	5,145,000	5,263,000	5,050,000
Funded status (net amount recognized):	(2,227,000)	(2,076,000)
Accumulated benefit obligations [Abstract]
Accumulated benefit obligations	7,400,000	7,300,000
Amounts recognized in balance sheet [Abstract]
Deferred tax assets	795,000	842,000
Accrued liabilities	2,227,000	2,076,000
Accumulated other comprehensive loss	(1,269,000)	(1,317,000)
Amounts recognized in other accumulated other comprehensive income (loss), before tax [Abstract]
Net actuarial loss	(936,000)	(948,000)
Unrecognized prior service cost	(333,000)	(369,000)
Total	$ (1,269,000)	$ (1,317,000)
Weighted average assumptions used in calculating benefit obligation [Abstract]
Discount rate (in hundredths)	4.60%	4.70%
Rate of compensation increase (in hundredths)	0.00%	0.00%
Defined benefit plan, weighted average assumptions used in calculating net periodic benefit cost [Abstract]
Discount rate (in hundredths)	4.70%	5.80%	6.00%
Expected return on plan assets (in hundredths)	4.00%	4.00%	5.00%
Rate of compensation increase (in hundredths)	0.00%	0.00%	0.00%