Segment and Geographic Data (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 31, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net revenues	$ 69,142	$ 67,421	$ 70,870	$ 76,525	$ 76,982	$ 75,490	$ 74,231	$ 73,091	$ 283,958	$ 299,794	$ 254,350
Gross profit	24,167	25,790	28,609	33,051	30,816	30,580	31,366	28,505	111,617	121,267	98,283
Segment operating income (loss)	1,757	6,186	8,102	12,603	7,091	10,631	11,315	8,186	28,648	37,223	22,488
Acquisition costs	443	0	0	0	0	0	0	0	443	0	0
Impairment of goodwill and indefinite-lived intangibles	0	0	0	0	2,820	0	0	0	0	2,820	0
Executive severance costs	0	0	611	0	0	0	0	0	611	0	0
Restructuring costs	1,746	$ 547	$ 0	$ 0	0	$ 228	$ 61	$ 0	2,293	289	2,044
Depreciation and amortization expense									11,795	10,631	10,626
Capital expenditures									10,529	13,239	10,092
Total assets	370,413				326,383				370,413	326,383	306,551
Foil Technology Products
Segment Reporting Information [Line Items]
Net revenues									131,803	141,009	116,273
Gross profit									53,292	61,562	47,755
Segment operating income (loss)									29,873	38,404	26,426
Acquisition costs									0
Impairment of goodwill and indefinite-lived intangibles										2,820
Executive severance costs									0
Restructuring costs									86	0	85
Depreciation and amortization expense									5,870	5,173	4,946
Capital expenditures									7,011	9,239	4,519
Total assets	116,920				132,918				116,920	132,918	119,175
Force Sensors
Segment Reporting Information [Line Items]
Net revenues									64,357	73,186	65,446
Gross profit									18,022	20,001	18,192
Segment operating income (loss)									8,643	10,514	9,274
Acquisition costs									0
Impairment of goodwill and indefinite-lived intangibles										0
Executive severance costs									0
Restructuring costs									2,041	289	849
Depreciation and amortization expense									2,442	2,323	2,537
Capital expenditures									2,237	2,483	4,297
Total assets	75,885				82,637				75,885	82,637	77,756
Weighing and Control Systems
Segment Reporting Information [Line Items]
Net revenues									87,798	85,599	72,631
Gross profit									40,303	39,704	32,336
Segment operating income (loss)									21,058	20,508	14,770
Acquisition costs									443
Impairment of goodwill and indefinite-lived intangibles										0
Executive severance costs									0
Restructuring costs									0	0	602
Depreciation and amortization expense									2,200	2,121	2,133
Capital expenditures									1,243	1,370	823
Total assets	158,597				95,954				158,597	95,954	97,007
Operating Segments | Foil Technology Products
Segment Reporting Information [Line Items]
Net revenues									131,803	141,009	116,272
Operating Segments | Force Sensors
Segment Reporting Information [Line Items]
Net revenues									64,357	73,186	65,446
Operating Segments | Weighing and Control Systems
Segment Reporting Information [Line Items]
Net revenues									87,798	85,599	72,632
Corporate/ Other
Segment Reporting Information [Line Items]
Net revenues									0	0	0
Gross profit									0	0	0
Segment operating income (loss)									(30,926)	(32,203)	(27,982)
Acquisition costs									0
Impairment of goodwill and indefinite-lived intangibles										0
Executive severance costs									611
Restructuring costs									166	0	508
Depreciation and amortization expense									1,283	1,014	1,010
Capital expenditures									38	147	453
Total assets	$ 19,011				$ 14,874				19,011	14,874	12,613
Intersegment revenues
Segment Reporting Information [Line Items]
Net revenues									(5,598)	(5,820)	(4,573)
Intersegment revenues | Foil Technology Products
Segment Reporting Information [Line Items]
Net revenues									4,067	3,878	2,316
Intersegment revenues | Force Sensors
Segment Reporting Information [Line Items]
Net revenues									1,068	1,365	1,346
Intersegment revenues | Weighing and Control Systems
Segment Reporting Information [Line Items]
Net revenues									$ 463	$ 577	$ 911