Revenue Disaggregation of Revenue (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Disaggregation of Revenue [Line Items]
Net sales		$ 98,058	$ 102,684	$ 196,236	$ 213,813
Applied Technology [Member]
Disaggregation of Revenue [Line Items]
Net sales		27,371	30,362	69,096	70,792
Aerostar [Member]
Disaggregation of Revenue [Line Items]
Net sales		13,189	13,517	25,379	24,418
Engineered Films [Member]
Disaggregation of Revenue [Line Items]
Net sales	[1]	57,516	58,875	101,808	118,867
All Segments [Member]
Disaggregation of Revenue [Line Items]
Net sales		98,058	102,684	196,236	213,813
UNITED STATES | Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Net sales		8,130	11,199	15,159	17,747
UNITED STATES | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales		54,825	54,851	96,558	109,954
UNITED STATES | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales		20,374	23,592	49,958	53,117
UNITED STATES | Other Product [Member]
Disaggregation of Revenue [Line Items]
Net sales		4,966	2,221	10,088	6,120
UNITED STATES | Applied Technology [Member] | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales		20,374	23,592	49,958	53,117
UNITED STATES | Aerostar [Member] | Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Net sales		8,130	11,199	15,159	17,747
UNITED STATES | Aerostar [Member] | Other Product [Member]
Disaggregation of Revenue [Line Items]
Net sales		4,966	2,221	10,088	6,120
UNITED STATES | Engineered Films [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales		54,843	54,921	96,605	110,218
Non-US [Member] | Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Net sales		15	82	49	536
Non-US [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales		2,673	3,954	5,203	8,649
Non-US [Member] | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales		6,997	6,770	19,138	17,675
Non-US [Member] | Other Product [Member]
Disaggregation of Revenue [Line Items]
Net sales		78	15	83	15
Non-US [Member] | Applied Technology [Member] | Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Net sales		6,997	6,770	19,138	17,675
Non-US [Member] | Aerostar [Member] | Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Net sales		15	82	49	536
Non-US [Member] | Aerostar [Member] | Other Product [Member]
Disaggregation of Revenue [Line Items]
Net sales		78	15	83	15
Non-US [Member] | Engineered Films [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales		2,673	3,954	5,203	8,649
Consolidation, Eliminations [Member]
Disaggregation of Revenue [Line Items]
Net sales	[2]	(18)	(70)	(47)	(264)
Consolidation, Eliminations [Member] | UNITED STATES | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales	[2]	(18)	(70)	(47)	(264)
Consolidation, Eliminations [Member] | Non-US [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Net sales		$ 0	$ 0	$ 0	$ 0

[1] Hurricane recovery film sales were $823 and $8,919 for the six-month periods ended July 31, 2019 and 2018. Hurricane recovery film sales were not significant in the three-month periods ended July 31, 2019 and 2018, respectively.

[2] Intersegment sales for both fiscal 2020 and 2019 were primarily sales from Engineered Films to Aerostar.