Note 17 - Segment and Geographic Information - Revenue by Region (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue	$ 153,497	$ 159,975	$ 139,761	$ 129,150	$ 129,430	$ 128,939	$ 112,198	$ 100,362	$ 582,382	$ 470,929	$ 388,665
CHINA
Revenue									334,726	257,787	245,169
TAIWAN, PROVINCE OF CHINA
Revenue									75,307	83,357	45,414
Europe [Member]
Revenue									49,484	38,140	27,554
KOREA, REPUBLIC OF
Revenue									41,238	34,155	27,710
South East Asia [Member]
Revenue									36,495	25,755	19,645
JAPAN
Revenue									26,853	20,187	14,318
UNITED STATES
Revenue									17,621	11,113	8,567
Other Region [Member]
Revenue									$ 658	$ 435	$ 288