Pension and Savings Plans - Weighted Average Asset Allocation for Pension Plan Assets (Detail) - USD ($) $ in Thousands	Aug. 26, 2017	Aug. 27, 2016	Aug. 29, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	$ 316,267	$ 289,386	$ 238,755
Asset allocation actual	100.00%	100.00%
Asset allocation target	100.00%	100.00%
U.S. Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	$ 50,125	$ 66,008
Asset allocation actual	15.80%	22.90%
Asset allocation target	17.00%	26.00%
International Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	$ 33,696	$ 42,023
Asset allocation actual	10.70%	14.50%
Asset allocation target	11.00%	17.00%
Emerging Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	$ 19,027	$ 22,848
Asset allocation actual	6.00%	7.90%
Asset allocation target	6.00%	8.50%
High Yield Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	$ 17,063	$ 21,445
Asset allocation actual	5.40%	7.40%
Asset allocation target	6.00%	8.50%
Fixed Income Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	$ 178,650	$ 99,336
Asset allocation actual	56.50%	34.30%
Asset allocation target	60.00%	40.00%
Cash and Cash Equivalents [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	$ 17,706	$ 37,726
Asset allocation actual	5.60%	13.00%
Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	$ 316,267	$ 289,386
Level 2 [Member] | U.S. Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	50,125	66,008
Level 2 [Member] | International Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	33,696	42,023
Level 2 [Member] | Emerging Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	19,027	22,848
Level 2 [Member] | High Yield Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	17,063	21,445
Level 2 [Member] | Fixed Income Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	178,650	99,336
Level 2 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Asset allocation fair value	$ 17,706	$ 37,726