BUSINESS SEGMENT AND INTERNATIONAL OPERATION INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Segment information
Net sales	$ 480,144	$ 454,364
Cost of sales	132,420	129,676
Volume incentives	144,591	140,589
Selling, general and administrative	178,390	164,004
Operating income	24,743	20,095
Interest and other income, net	645	177
Interest expense	(98)	(146)
Foreign exchange gains (losses), net	4,522	(1,700)
Income from operations before provision for income taxes	29,812	18,426
Depreciation and amortization:
Total depreciation and amortization	13,844	14,219
Property, plant and equipment, net
Total property, plant and equipment, net	32,915	39,585
Operating Segments
Segment information
Net sales	480,144	454,364
Operating income	80,301	70,987
Depreciation and amortization:
Total depreciation and amortization	13,844	14,219
Unallocated corporate selling, general and administrative expense
Segment information
Selling, general and administrative	(55,558)	(50,892)
General health | Operating Segments
Segment information
Net sales	192,122	183,882
Immune | Operating Segments
Segment information
Net sales	40,818	38,724
Cardiovascular | Operating Segments
Segment information
Net sales	81,635	81,700
Digestive | Operating Segments
Segment information
Net sales	124,368	111,744
Personal care | Operating Segments
Segment information
Net sales	23,267	17,803
Weight management | Operating Segments
Segment information
Net sales	17,934	20,511
Asia | Operating Segments
Segment information
Net sales	221,777	207,794
Cost of sales	48,484	48,557
Volume incentives	71,185	69,685
Selling, general and administrative	61,944	55,443
Operating income	40,164	34,109
Depreciation and amortization:
Total depreciation and amortization	1,896	1,876
Asia | General health | Operating Segments
Segment information
Net sales	83,632	81,313
Asia | Immune | Operating Segments
Segment information
Net sales	14,438	12,052
Asia | Cardiovascular | Operating Segments
Segment information
Net sales	54,555	56,266
Asia | Digestive | Operating Segments
Segment information
Net sales	47,673	38,958
Asia | Personal care | Operating Segments
Segment information
Net sales	10,074	5,032
Asia | Weight management | Operating Segments
Segment information
Net sales	11,405	14,173
Europe | Operating Segments
Segment information
Net sales	93,133	84,837
Cost of sales	27,524	27,836
Volume incentives	37,359	33,758
Selling, general and administrative	20,203	18,577
Operating income	8,047	4,666
Depreciation and amortization:
Total depreciation and amortization	99	93
Europe | General health | Operating Segments
Segment information
Net sales	39,794	36,631
Europe | Immune | Operating Segments
Segment information
Net sales	9,148	8,454
Europe | Cardiovascular | Operating Segments
Segment information
Net sales	10,805	9,265
Europe | Digestive | Operating Segments
Segment information
Net sales	24,601	22,748
Europe | Personal care | Operating Segments
Segment information
Net sales	5,813	5,397
Europe | Weight management | Operating Segments
Segment information
Net sales	2,972	2,342
North America | Operating Segments
Segment information
Net sales	143,611	138,849
Cost of sales	48,528	45,364
Volume incentives	29,485	29,773
Selling, general and administrative	34,736	32,793
Operating income	30,862	30,919
Depreciation and amortization:
Total depreciation and amortization	11,801	12,204
North America | General health | Operating Segments
Segment information
Net sales	62,226	59,520
North America | Immune | Operating Segments
Segment information
Net sales	15,385	15,802
North America | Cardiovascular | Operating Segments
Segment information
Net sales	14,661	14,443
North America | Digestive | Operating Segments
Segment information
Net sales	41,804	39,325
North America | Personal care | Operating Segments
Segment information
Net sales	6,474	6,241
North America | Weight management | Operating Segments
Segment information
Net sales	3,061	3,518
Latin America and Other | Operating Segments
Segment information
Net sales	21,623	22,884
Cost of sales	7,884	7,918
Volume incentives	6,562	7,374
Selling, general and administrative	5,949	6,299
Operating income	1,228	1,293
Depreciation and amortization:
Total depreciation and amortization	48	46
Latin America and Other | General health | Operating Segments
Segment information
Net sales	6,470	6,418
Latin America and Other | Immune | Operating Segments
Segment information
Net sales	1,847	2,416
Latin America and Other | Cardiovascular | Operating Segments
Segment information
Net sales	1,614	1,726
Latin America and Other | Digestive | Operating Segments
Segment information
Net sales	10,290	10,713
Latin America and Other | Personal care | Operating Segments
Segment information
Net sales	906	1,133
Latin America and Other | Weight management | Operating Segments
Segment information
Net sales	496	478
China
Segment information
Selling, general and administrative	16,800	14,500
United States
Segment information
Net sales	133,387	127,924
Property, plant and equipment, net
Total property, plant and equipment, net	29,061	34,786
Taiwan
Segment information
Net sales	67,280	70,579
Japan
Segment information
Net sales	56,070	43,940
Korea
Segment information
Net sales	50,842	51,362
Other
Segment information
Net sales	172,565	160,559
Other
Property, plant and equipment, net
Total property, plant and equipment, net	$ 3,854	$ 4,799