Income Taxes (Reconciliation of U.S. Statutory Income Tax Rate) (Details)	12 Months Ended
	Aug. 26, 2017	Aug. 27, 2016	Aug. 29, 2015
Income Tax Disclosure [Abstract]
US federal statutory rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	2.80%	2.50%	2.40%
Tax-free and dividend income	(0.70%)	(1.30%)	(1.30%)
Income tax credits	(0.60%)	(1.10%)	(0.30%)
Domestic production activities deduction	(2.40%)	(2.50%)	(3.70%)
Other items	0.80%	(1.30%)	(0.80%)
Uncertain tax positions settlements and adjustments	(0.60%)	0.00%	(0.50%)
Effective tax provision rate	34.30%	31.30%	30.80%