Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Condensed Consolidated Balance Sheets
Accounts receivable, allowance for doubtful accounts	$ 1,718	$ 1,224
Property, plant and equipment, accumulated depreciation	175,014	173,699
Other intangible assets, accumulated amortization	9,815	9,774
Other long-term liabilities, deferred income taxes	$ 63,464	$ 59,532
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	250,000,000us-gaap_CommonStockSharesAuthorized	250,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued (in shares)	119,792,881us-gaap_CommonStockSharesIssued	119,606,551us-gaap_CommonStockSharesIssued
Treasury stock, shares (in shares)	57,862,185us-gaap_TreasuryStockShares	57,832,362us-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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Face amount or stated value per share of common stock.

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Amount of deferred tax liability attributable to taxable temporary differences, net of deferred tax asset attributable to deductible temporary differences and carryforwards net of valuation allowances expected to be realized or consumed after one year (or the normal operating cycle, if longer).

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