Consolidated Balance Sheets (Parentheticals) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Preferred stock, par value per share	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000us-gaap_PreferredStockSharesAuthorized	5,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, shares issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000us-gaap_CommonStockSharesAuthorized	400,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	156,716,000us-gaap_CommonStockSharesIssued	155,246,000us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	83,147,000us-gaap_CommonStockSharesOutstanding	84,819,000us-gaap_CommonStockSharesOutstanding
Treasury stock, shares	73,569,000us-gaap_TreasuryStockShares	70,427,000us-gaap_TreasuryStockShares

Face amount or stated value per share of common stock.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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