Revenue Disaggregation of Revenue (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
Disaggregation of Revenue [Line Items]
Net sales		$ 102,684	$ 86,610	$ 213,813	$ 180,145
Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		11,199	5,460	17,747	11,666
International Net Sales		82	28	536	54
Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		54,851	45,032	109,954	86,027
International Net Sales		3,954	3,785	8,649	6,229
Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		23,592	20,742	53,117	51,000
International Net Sales		6,770	7,682	17,675	17,914
Other Product [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		2,221	3,881	6,120	7,213
International Net Sales		15	0	15	42
Engineered Films Plastic Films & Sheeting [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		54,921	45,243	110,218	86,354
International Net Sales		3,954	3,785	8,649	6,229
Net sales		58,875	49,028	118,867	92,583
Applied Technology Precision Agriculture Equipment [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		23,592	20,742	53,117	51,000
International Net Sales		6,770	7,682	17,675	17,914
Net sales		30,362	28,424	70,792	68,914
Aerostar Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		11,199	5,460	17,747	11,666
International Net Sales		82	28	536	54
Aerostar Other [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		2,221	3,881	6,120	7,213
International Net Sales		15	0	15	42
Aerostar [Member]
Disaggregation of Revenue [Line Items]
Net sales		13,517	9,369	24,418	18,975
Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Net sales	[1],[2]	(70)	(211)	(264)	(327)
Intersegment Eliminations [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales	[1]	(70)	(211)	(264)	(327)
International Net Sales	[1]	0	0	0	0
All Segments [Member]
Disaggregation of Revenue [Line Items]
Net sales		$ 102,684	$ 86,610	$ 213,813	$ 180,145

[1] Intersegment sales for both fiscal 2019 and 2018 were primarily sales from Engineered Films to Aerostar.

[2] Intersegment sales for both fiscal 2019 and 2018 were primarily sales from Engineered Films to Aerostar.