Revenue Disaggregation of Revenue (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Disaggregation of Revenue [Line Items]
Net sales		$ 104,833	$ 101,349	$ 318,646	$ 281,494
Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		14,152	7,443	31,899	19,109
International Net Sales		298	33	834	87
Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		52,664	62,240	162,618	148,267
International Net Sales		5,398	2,687	14,047	8,916
Precision Agriculture [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		23,764	20,079	76,881	71,079
International Net Sales		5,976	5,240	23,651	23,154
Other Product [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		2,578	3,615	8,698	10,828
International Net Sales		3	12	18	54
Engineered Films Plastic Films & Sheeting [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		52,841	62,421	163,059	148,775
International Net Sales		5,398	2,687	14,047	8,916
Net sales		58,239	65,108	177,106	157,691
Applied Technology Precision Agriculture Equipment [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		23,764	20,079	76,881	71,079
International Net Sales		5,976	5,240	23,651	23,154
Net sales		29,740	25,319	100,532	94,233
Aerostar Lighter-than-air [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		14,152	7,443	31,899	19,109
International Net Sales		298	33	834	87
Aerostar Other [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales		2,578	3,615	8,698	10,828
International Net Sales		3	12	18	54
Aerostar [Member]
Disaggregation of Revenue [Line Items]
Net sales		17,031	11,103	41,449	30,078
Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Net sales	[1],[2]	(177)	(181)	(441)	(508)
Intersegment Eliminations [Member] | Plastic Films and Sheeting [Member]
Disaggregation of Revenue [Line Items]
Domestic Net Sales	[1]	(177)	(181)	(441)	(508)
International Net Sales		0	0	0	0
All Segments [Member]
Disaggregation of Revenue [Line Items]
Net sales		$ 104,833	$ 101,349	$ 318,646	$ 281,494

[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.