Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 26, 2020	Dec. 28, 2019
Allowance on trade accounts receivable	$ 8,670	$ 7,284
Allowance on other receivables	7,239	7,667
Accumulated depreciation and amortization on operating property	$ 299,407	$ 280,849
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized shares	160,000,000	160,000,000
Common stock, issued shares	68,183,702	68,083,419
Treasury stock, shares	29,797,639	28,609,926

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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