Note 2 - Summary of Significant Accounting Policies - Warranty Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2017
Balance at beginning of the period	$ 7,560	$ 5,069	$ 5,069
Additions charged to expense	2,394	2,243	4,956
Addition from acquired company			907
Deductions for repairs and replacements	(3,266)	(1,351)	(3,372)
Balance at end of the period	$ 6,688	$ 5,961	$ 7,560