Note 17 - Segment and Geographic Information - Revenue by Product Family (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue	$ 103,618	$ 106,456	$ 94,079	$ 84,512	$ 86,918	$ 91,194	$ 81,416	$ 73,538	$ 388,665	$ 333,067	$ 282,535
DC To DC Products [Member]
Revenue									350,930	299,726	253,083
Lighting Control Products [Member]
Revenue									$ 37,735	$ 33,341	$ 29,452