Tax Effect of Temporary Differences That Give Rise to Deferred Tax Assets and Deferred Tax Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 26, 2015
Deferred tax assets:
Self-insurance reserves	$ 119,613	$ 118,082
Retirement plan contributions	63,432	61,898
Postretirement benefit cost	41,362	40,883
Investment tax credits	33,170	6,832
Inventory capitalization	18,294	15,072
Purchase allowances	18,005	13,792
Leases	15,903	19,250
Reserves not currently deductible	8,675	10,873
Other	3,649	1,489
Total deferred tax assets	322,103	288,171
Deferred tax liabilities:
Property, plant and equipment, primarily due to depreciation	704,233	615,408
Other	14,354	46,679
Total deferred tax liabilities	$ 718,587	$ 662,087