Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Property and equipment, accumulated depreciation	$ 65,460	$ 58,357
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	70,000,000	70,000,000
Common stock, shares issued (in shares)	21,278,102	21,035,654
Common stock, shares outstanding (in shares)	19,400,014	19,430,154