Note 1 - Description of Business and Summary of Significant Accounting Policies - Reconciliation of Basic to Diluted Weighted-average Shares Outstanding (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted-average shares outstanding, basic (in shares)	88,084	73,061	71,848
Weighted-average shares underlying stock options and restricted shares (in shares)	694	775	916
Weighted-average shares outstanding, diluted (in shares)	88,778	73,836	72,764