Note 17 - Segment and Geographic Information (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]

	Year Ended December 31,
Country or Region	2017		2016		2015
China	$	257,787	$	245,169	$	213,119
Taiwan		83,357		45,414		41,521
Europe		38,140		27,554		22,603
Korea		34,155		27,710		20,519
Southeast Asia		25,755		19,645		18,592
Japan		20,187		14,318		9,727
United States		11,113		8,567		6,732
Other		435		288		254
Total	$	470,929	$	388,665	$	333,067

Revenue from External Customers by Products and Services [Table Text Block]

	Year Ended December 31,
Product Family	2017		2016		2015
DC to DC	$	431,861	$	350,930	$	299,726
Lighting Control		39,068		37,735		33,341
Total	$	470,929	$	388,665	$	333,067

Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block]

	December 31,
Country	2017		2016		2015
China	$	89,472	$	45,728	$	40,738
United States		65,618		50,242		40,405
Taiwan		17,238		8,919		126
Bermuda		7,522		9,573		11,624
Other		388		571		431
Total	$	180,238	$	115,033	$	93,324