Note 4 - Supplemental Cash Flow Information (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Taxes Paid			$ 3,748,000	$ 3,173,000
Interest Paid			$ 313,000	$ 278,000
Stock Issued During Period, Shares, New Issues	71,599	30,416	113,143	30,416
Company Stock Received in Lieu of Cash Stock Options Exercised	27,341	10,434	43,841	10,434