Segment and Geographic Data (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 29, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net revenues		$ 269,812	$ 283,958	$ 299,794
Gross profit		104,271	111,617	121,267
Segment operating income (loss)		22,657	28,648	37,223
Acquisition costs		0	443	0
Impairment of goodwill and indefinite-lived intangibles		2,440	0	2,820
Executive severance costs	$ 600	0	611	0
Restructuring costs		918	2,293	289
Depreciation and amortization expense		12,507	11,795	10,631
Capital expenditures		24,327	10,529	13,239
Total assets		401,887	370,413	326,383
Foil Technology Products
Segment Reporting Information [Line Items]
Net revenues		131,645	131,803	141,009
Gross profit		52,025	53,292	61,562
Segment operating income (loss)		29,870	29,873	38,404
Acquisition costs			0
Impairment of goodwill and indefinite-lived intangibles		2,440		2,820
Executive severance costs			0
Restructuring costs		572	86	0
Depreciation and amortization expense		5,840	5,870	5,173
Capital expenditures		22,032	7,011	9,239
Total assets		157,120	116,920	132,918
Force Sensors
Segment Reporting Information [Line Items]
Net revenues		53,724	64,357	73,186
Gross profit		13,582	18,022	20,001
Segment operating income (loss)		4,756	8,643	10,514
Acquisition costs			0
Impairment of goodwill and indefinite-lived intangibles		0		0
Executive severance costs			0
Restructuring costs		108	2,041	289
Depreciation and amortization expense		2,367	2,442	2,323
Capital expenditures		1,211	2,237	2,483
Total assets		63,461	75,885	82,637
Weighing and Control Systems
Segment Reporting Information [Line Items]
Net revenues		84,443	87,798	85,599
Gross profit		38,664	40,303	39,704
Segment operating income (loss)		18,768	21,058	20,508
Acquisition costs			443
Impairment of goodwill and indefinite-lived intangibles		0		0
Executive severance costs			0
Restructuring costs		156	0	0
Depreciation and amortization expense		2,964	2,200	2,121
Capital expenditures		1,071	1,243	1,370
Total assets		157,840	158,597	95,954
Operating Segments | Foil Technology Products
Segment Reporting Information [Line Items]
Net revenues		131,645	131,803	141,009
Operating Segments | Force Sensors
Segment Reporting Information [Line Items]
Net revenues		53,724	64,357	73,186
Operating Segments | Weighing and Control Systems
Segment Reporting Information [Line Items]
Net revenues		84,443	87,798	85,599
Corporate/ Other
Segment Reporting Information [Line Items]
Net revenues		0	0	0
Gross profit		0	0	0
Segment operating income (loss)		(30,737)	(30,926)	(32,203)
Acquisition costs			0
Impairment of goodwill and indefinite-lived intangibles		0		0
Executive severance costs			611
Restructuring costs		82	166	0
Depreciation and amortization expense		1,336	1,283	1,014
Capital expenditures		13	38	147
Total assets		23,466	19,011	14,874
Intersegment revenues
Segment Reporting Information [Line Items]
Net revenues		(3,629)	(5,598)	(5,820)
Intersegment revenues | Foil Technology Products
Segment Reporting Information [Line Items]
Net revenues		3,183	4,067	3,878
Intersegment revenues | Force Sensors
Segment Reporting Information [Line Items]
Net revenues		0	1,068	1,365
Intersegment revenues | Weighing and Control Systems
Segment Reporting Information [Line Items]
Net revenues		$ 446	$ 463	$ 577