Note 5 - Earnings Per Share ("EPS") - Basic and Diluted Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic weighted average common shares outstanding (in shares)									14,575	14,682	14,934
Effect of dilutive securities:
Stock options, SAR's, RSA's and RSU's (in shares)									493	434	387
Diluted shares used in the calculation of earnings per share (in shares)	15,141	15,115	15,044	15,043	14,979	15,077	15,111	15,307	15,068	15,116	15,321