Note 10 - Segment Information and Revenue by Geography and Products - Revenue by Geographic Region (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue from Contract with Customer, Including Assessed Tax	$ 162,720	$ 151,493	$ 118,056
Products [Member]
Revenue from Contract with Customer, Including Assessed Tax	132,594	125,883	92,721
Hand Piece Refills [Member]
Revenue from Contract with Customer, Including Assessed Tax	4,162	2,435	2,498
Skincare [Member]
Revenue from Contract with Customer, Including Assessed Tax	5,778	4,342	3,809
Total Product Revenue [Member]
Revenue from Contract with Customer, Including Assessed Tax	142,535	132,660	99,028
Service [Member]
Revenue from Contract with Customer, Including Assessed Tax	20,185	18,833	19,028
UNITED STATES
Revenue from Contract with Customer, Including Assessed Tax	101,862	94,581	65,513
JAPAN
Revenue from Contract with Customer, Including Assessed Tax	17,819	17,264	14,727
Asia, Excluding Japan [Member]
Revenue from Contract with Customer, Including Assessed Tax	15,467	13,719	13,445
Europe [Member]
Revenue from Contract with Customer, Including Assessed Tax	8,875	8,317	7,539
Rest of World [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ 18,696	$ 17,612	$ 16,832