Note 16 - Segment and Geographic Information - Revenue by Region (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue	$ 166,738	$ 168,813	$ 151,007	$ 141,363	$ 153,497	$ 159,975	$ 139,761	$ 129,150	$ 627,921	$ 582,382	$ 470,929
CHINA
Revenue									382,740	334,726	257,787
TAIWAN, PROVINCE OF CHINA
Revenue									73,801	75,307	83,357
Europe [Member]
Revenue									49,467	49,484	38,140
KOREA, REPUBLIC OF
Revenue									43,900	41,238	34,155
South East Asia [Member]
Revenue									32,031	36,495	25,755
JAPAN
Revenue									27,812	26,853	20,187
UNITED STATES
Revenue									17,836	17,621	11,113
Other Region [Member]
Revenue									$ 334	$ 658	$ 435