Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	200,000us-gaap_CommonStockSharesAuthorized	200,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued (in shares)	46,410us-gaap_CommonStockSharesIssued	46,410us-gaap_CommonStockSharesIssued
Common stock, shares outstanding (in shares)	40,738us-gaap_CommonStockSharesOutstanding	41,176us-gaap_CommonStockSharesOutstanding	43,284us-gaap_CommonStockSharesOutstanding
Treasury stock, at cost (in shares)	5,672us-gaap_TreasuryStockShares	5,234us-gaap_TreasuryStockShares	3,126us-gaap_TreasuryStockShares

Face amount or stated value per share of common stock.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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