Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Net sales	$ 534,792	$ 639,813	$ 654,233
Cost of sales	332,434	423,964	470,780
Gross profit	202,358	215,849	183,453
Research and development costs	23,586	22,487	20,238
Selling, general and administrative expenses	110,616	99,091	92,342
Impairment of CUI tradename	400	0	0
Restructuring charges	3,459	10,114	7,322
Gain on sale of properties	0	(3,819)	(1,596)
Income from operations	64,297	87,976	65,147
Gain on sale of Czech Republic business	0	980	0
Interest expense	(4,078)	(2,850)	(3,379)
Interest income	4,754	1,697	177
Other expense, net	(3,165)	(4,503)	(2,886)
Earnings before provision for income taxes	61,808	83,300	59,059
Provision for income taxes	12,616	9,469	6,370
Net earnings available to common shareholders	49,192	73,831	52,689
Less: Net earnings attributable to noncontrolling interest	484	0	0
Redemption value adjustment attributable to noncontrolling interest	7,748	0	0
Net earnings attributable to Bel Fuse shareholders	$ 40,960	$ 73,831	$ 52,689
Common Class A [Member]
Net earnings per common share:
Net earnings per common share - basic and diluted (in dollars per share)	$ 3.1	$ 5.52	$ 4.01
Weighted-average shares outstanding:
Weighted-average number of shares outstanding - basic and diluted (in shares)	2,124	2,142	2,143
Common Class B [Member]
Net earnings per common share:
Net earnings per common share - basic and diluted (in dollars per share)	$ 3.28	$ 5.83	$ 4.24
Weighted-average shares outstanding:
Weighted-average number of shares outstanding - basic and diluted (in shares)	10,491	10,634	10,394