Income Taxes - Tax Effect of Temporary Differences and Carryforwards which Give Rise to Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 24, 2016	Sep. 26, 2015
Current:
Allowance for doubtful accounts, Deferred Tax Assets	$ 7,634	$ 7,054
Inventory write-downs, Deferred Tax Assets	9,869	11,366
Prepaid expenses, Deferred Tax Assets	0	0
Nondeductible reserves, Deferred Tax Assets	1,632	936
State taxes, Deferred Tax Assets	19	0
Employee benefits, Deferred Tax Assets	10,544	9,411
Other, Deferred Tax Assets	3,000	2,754
Total, Current, Deferred Tax Assets	32,698	31,521
Allowance for doubtful accounts, Deferred Tax Liabilities	0	0
Inventory write-downs, Deferred Tax Liabilities	0	0
Prepaid expenses, Deferred Tax Liabilities	1,188	651
Nondeductible reserves, Deferred Tax Liabilities	0	0
State taxes, Deferred Tax Liabilities	0	385
Employee benefits, Deferred Tax Liabilities	0	0
Other, Deferred Tax Liabilities	0	0
Total, Current, Deferred Tax Liabilities	1,188	1,036
Noncurrent:
Depreciation and amortization, Deferred Tax Assets	0	0
Equity loss, Deferred Tax Assets	5,070	0
State net operating loss carryforward, Deferred Tax Assets	4,939	5,032
Stock based compensation, Deferred Tax Assets	2,642	3,422
State credits, Deferred Tax Assets	2,317	2,348
Other, Deferred Tax Assets	2,303	2,463
Valuation allowance, Deferred Tax Assets	(6,583)	(6,205)
Total, Noncurrent, Deferred Tax Assets	10,688	7,060
Depreciation and amortization, Deferred Tax Liabilities	62,778	52,415
Equity loss, Deferred Tax Liabilities	0	305
State net operating loss carryforward, Deferred Tax Liabilities	0	0
Stock based compensation, Deferred Tax Liabilities	0	0
State credits, Deferred Tax Liabilities	0	0
Other, Deferred Tax Liabilities	0	0
Valuation allowance, Deferred Tax Liabilities	0	0
Total, Noncurrent, Deferred Tax Liabilities	62,778	52,720
Total, Deferred Tax Assets	43,386	38,581
Total, Deferred Tax Liabilities	$ 63,966	$ 53,756