Revenue Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Disaggregation of Revenue [Line Items]
Net sales	$ 85,179	$ 98,058	$ 171,675	$ 196,236
Applied Technology [Member]
Disaggregation of Revenue [Line Items]
Net sales	35,502	27,371	77,509	69,096
Aerostar [Member]
Disaggregation of Revenue [Line Items]
Net sales	13,465	13,189	24,616	25,379
Engineered Films [Member]
Disaggregation of Revenue [Line Items]
Net sales	36,252	57,516	69,650	101,808
All Segments [Member]
Disaggregation of Revenue [Line Items]
Net sales	85,179	98,058	171,675	196,236
UNITED STATES | Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Net sales	10,008	8,130	16,090	15,159
UNITED STATES | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	32,440	54,825	62,936	96,558
UNITED STATES | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales	27,998	20,374	58,859	49,958
UNITED STATES | Other Product [Member]
Disaggregation of Revenue [Line Items]
Net sales	3,423	4,966	8,475	10,088
UNITED STATES | Applied Technology [Member] | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales	28,000	20,374	58,861	49,958
UNITED STATES | Aerostar [Member] | Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Net sales	10,008	8,130	16,090	15,159
UNITED STATES | Aerostar [Member] | Other Product [Member]
Disaggregation of Revenue [Line Items]
Net sales	3,423	4,966	8,475	10,088
UNITED STATES | Engineered Films [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	32,478	54,843	63,034	96,605
Non-US [Member] | Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Net sales	34	15	46	49
Non-US [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	3,774	2,673	6,616	5,203
Non-US [Member] | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales	7,502	6,997	18,648	19,138
Non-US [Member] | Other Product [Member]
Disaggregation of Revenue [Line Items]
Net sales	0	78	5	83
Non-US [Member] | Applied Technology [Member] | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales	7,502	6,997	18,648	19,138
Non-US [Member] | Aerostar [Member] | Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Net sales	34	15	46	49
Non-US [Member] | Aerostar [Member] | Other Product [Member]
Disaggregation of Revenue [Line Items]
Net sales	0	78	5	83
Non-US [Member] | Engineered Films [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	3,774	2,673	6,616	5,203
Consolidation, Eliminations [Member]
Disaggregation of Revenue [Line Items]
Net sales	(40)	(18)	(100)	(47)
Consolidation, Eliminations [Member] | UNITED STATES | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	(38)	(18)	(98)	(47)
Consolidation, Eliminations [Member] | UNITED STATES | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales	(2)	0	(2)	0
Consolidation, Eliminations [Member] | Non-US [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 0	$ 0	$ 0	$ 0