Revenue Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Disaggregation of Revenue [Line Items]
Net sales	$ 100,533	$ 104,833	$ 296,769	$ 318,646
Applied Technology [Member]
Disaggregation of Revenue [Line Items]
Net sales	28,500	29,740	97,596	100,532
Aerostar [Member]
Disaggregation of Revenue [Line Items]
Net sales	15,661	17,031	41,040	41,449
Engineered Films [Member]
Disaggregation of Revenue [Line Items]
Net sales	56,406	58,239	158,214	177,106
All Segments [Member]
Disaggregation of Revenue [Line Items]
Net sales	100,533	104,833	296,769	318,646
UNITED STATES | Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Net sales	11,071	14,152	26,230	31,899
UNITED STATES | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	54,640	52,664	151,198	162,618
UNITED STATES | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales	22,956	23,764	72,914	76,881
UNITED STATES | Other Product [Member]
Disaggregation of Revenue [Line Items]
Net sales	4,577	2,578	14,665	8,698
UNITED STATES | Applied Technology [Member] | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales	22,957	23,764	72,915	76,881
UNITED STATES | Aerostar [Member] | Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Net sales	11,071	14,152	26,230	31,899
UNITED STATES | Aerostar [Member] | Other Product [Member]
Disaggregation of Revenue [Line Items]
Net sales	4,577	2,578	14,665	8,698
UNITED STATES | Engineered Films [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	54,673	52,841	151,278	163,059
Non-US [Member] | Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Net sales	0	298	49	834
Non-US [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	1,733	5,398	6,936	14,047
Non-US [Member] | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales	5,543	5,976	24,681	23,651
Non-US [Member] | Other Product [Member]
Disaggregation of Revenue [Line Items]
Net sales	13	3	96	18
Non-US [Member] | Applied Technology [Member] | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales	5,543	5,976	24,681	23,651
Non-US [Member] | Aerostar [Member] | Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Net sales	0	298	49	834
Non-US [Member] | Aerostar [Member] | Other Product [Member]
Disaggregation of Revenue [Line Items]
Net sales	13	3	96	18
Non-US [Member] | Engineered Films [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	1,733	5,398	6,936	14,047
Consolidation, Eliminations [Member]
Disaggregation of Revenue [Line Items]
Net sales	(34)	(177)	(81)	(441)
Consolidation, Eliminations [Member] | UNITED STATES | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	(33)	(177)	(80)	(441)
Consolidation, Eliminations [Member] | UNITED STATES | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales	(1)	0	(1)	0
Consolidation, Eliminations [Member] | Non-US [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 0	$ 0	$ 0	$ 0