Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Property and equipment, accumulated depreciation	$ 61,983	$ 58,357
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000us-gaap_PreferredStockSharesAuthorized	5,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, shares issued (in shares)	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	70,000,000us-gaap_CommonStockSharesAuthorized	70,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued (in shares)	21,213,939us-gaap_CommonStockSharesIssued	21,035,654us-gaap_CommonStockSharesIssued
Common stock, shares outstanding (in shares)	19,522,388us-gaap_CommonStockSharesOutstanding	19,430,154us-gaap_CommonStockSharesOutstanding

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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