Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 27, 2014	Dec. 28, 2013
Allowance on trade accounts receivable	$ 4,338	$ 3,773
Allowance on other receivables	4,189	4,253
Accumulated depreciation and amortization on operating property	$ 160,681	$ 157,985
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized shares	160,000,000us-gaap_CommonStockSharesAuthorized	160,000,000us-gaap_CommonStockSharesAuthorized
Common stock, issued shares	67,268,817us-gaap_CommonStockSharesIssued	67,017,858us-gaap_CommonStockSharesIssued
Treasury stock, shares	22,474,331us-gaap_TreasuryStockShares	21,528,693us-gaap_TreasuryStockShares

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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The valuation allowance as of the balance sheet date to reduce the gross amount of receivables to estimated net realizable value, which would be presented in parentheses on the face of the balance sheet.

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A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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Face amount or stated value per share of common stock.

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