Note 7 - Segment and Geographic Information (Details) - Revenue by Product Family - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenue from External Customer [Line Items]
Product family	$ 91,194	$ 78,335	$ 246,148	$ 206,832
DC To DC Products [Member]
Revenue from External Customer [Line Items]
Product family	82,718	70,196	222,210	185,304
Lighting Control Products [Member]
Revenue from External Customer [Line Items]
Product family	$ 8,476	$ 8,139	$ 23,938	$ 21,528