Annual report pursuant to Section 13 and 15(d)

Income Taxes - Reconciliation of the Statutory Federal Income Tax Rate to the Company's Effective Income Tax Rate (Detail)

v3.8.0.1
Income Taxes - Reconciliation of the Statutory Federal Income Tax Rate to the Company's Effective Income Tax Rate (Detail)
12 Months Ended
Sep. 30, 2017
Sep. 24, 2016
Sep. 26, 2015
Income Tax Disclosure [Abstract]      
Statutory federal income tax rate 35.00% 35.00% 35.00%
State income taxes, net of federal benefit 2.40% 2.10% 2.40%
Other permanent differences 0.30% (1.60%) (0.50%)
Adjustment of prior year accruals (0.30%) (0.60%) (0.50%)
Credits (0.60%) (1.00%) (0.30%)
Change in valuation allowances 0.00% 0.50% 0.00%
Foreign rate differential 0.10% 0.10% (0.10%)
Effective income tax rate (benefit) 36.90% 34.50% 36.00%