Note 17 - Segment and Geographic Information - Revenue by Region (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue	$ 129,430	$ 128,939	$ 112,198	$ 100,362	$ 103,618	$ 106,456	$ 94,079	$ 84,512	$ 470,929	$ 388,665	$ 333,067
CHINA
Revenue									257,787	245,169	213,119
TAIWAN, PROVINCE OF CHINA
Revenue									83,357	45,414	41,521
Europe [Member]
Revenue									38,140	27,554	22,603
KOREA, REPUBLIC OF
Revenue									34,155	27,710	20,519
South East Asia [Member]
Revenue									25,755	19,645	18,592
JAPAN
Revenue									20,187	14,318	9,727
UNITED STATES
Revenue									11,113	8,567	6,732
Other Region [Member]
Revenue									$ 435	$ 288	$ 254