Consolidated Balance Sheets (Parentheticals) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	40,000,000	40,000,000
Common stock, shares issued (in shares)	25,013,067	25,022,312
Common stock, shares outstanding (in shares)	17,922,137	17,993,124
Treasury stock, shares (in shares)	7,090,930	7,029,188