Pension and Savings Plans - Plan's Funded Status and Amounts Recognized in Company's Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Aug. 26, 2017	Aug. 27, 2016	Aug. 29, 2015
Change in Projected Benefit Obligation:
Projected benefit obligation at beginning of year	$ 328,511	$ 296,123
Interest cost	10,335	11,272	$ 12,338
Actuarial (gains) losses	(8,746)	39,842
Benefits paid	(15,376)	(18,726)
Benefit obligations at end of year	314,724	328,511	296,123
Change in Plan Assets:
Fair value of plan assets at beginning of year	289,386	238,755
Actual return on plan assets	24,496	16,636
Employer contributions	17,761	52,721	17,100
Benefits paid	(15,376)	(18,726)
Fair value of plan assets at end of year	316,267	289,386	$ 238,755
Amount Recognized in the Statement of Financial Position:
Current liabilities	(283)	(276)
Long-term assets	8,686
Long-term liabilities	(6,860)	(38,849)
Net amount recognized	1,543	(39,125)
Amount Recognized in Accumulated Other Comprehensive Loss and not yet reflected in Net Periodic Benefit Cost:
Net actuarial loss	(118,889)	(145,948)
Accumulated other comprehensive loss	(118,889)	(145,948)
Amount Recognized in Accumulated Other Comprehensive Loss and not yet reflected in Net Periodic Benefit Cost and expected to be amortized in next year's Net Periodic Benefit Cost:
Net actuarial loss	(10,736)	(13,874)
Amount recognized	$ (10,736)	$ (13,874)