Note 14 - Segment Reporting - Revenue by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue mix by geography:
Revenue mix	$ 40,573	$ 38,173	$ 117,251	$ 103,861
Products [Member]
Revenue mix by geography:
Revenue mix	33,197	31,861	95,727	84,969
Hand Piece Refills [Member]
Revenue mix by geography:
Revenue mix	1,055	596	2,881	1,743
Skincare [Member]
Revenue mix by geography:
Revenue mix	1,423	1,029	3,981	2,976
Total Product Revenue [Member]
Revenue mix by geography:
Revenue mix	35,675	33,486	102,589	89,688
Service [Member]
Revenue mix by geography:
Revenue mix	4,898	4,687	14,662	14,173
UNITED STATES
Revenue mix by geography:
Revenue mix	24,329	23,275	73,597	64,058
JAPAN
Revenue mix by geography:
Revenue mix	5,021	4,686	12,522	12,276
Asia, Excluding Japan [Member]
Revenue mix by geography:
Revenue mix	4,348	3,488	11,422	9,501
Europe [Member]
Revenue mix by geography:
Revenue mix	2,356	2,024	6,729	5,469
Rest of World [Member]
Revenue mix by geography:
Revenue mix	$ 4,519	$ 4,700	$ 12,981	$ 12,557