Revenue Revenue by Product Category (Details) $ in Thousands		3 Months Ended																12 Months Ended
		Jan. 31, 2019 USD ($)	[1]	Oct. 31, 2018 USD ($)	[1],[2]	Jul. 31, 2018 USD ($)	[2]	Apr. 30, 2018 USD ($)	[2]	Jan. 31, 2018 USD ($)	[1]	Oct. 31, 2017 USD ($)	[1],[2]	Jul. 31, 2017 USD ($)	[2]	Apr. 30, 2017 USD ($)	[2]	Jan. 31, 2019 USD ($) Divisions		Jan. 31, 2018 USD ($)		Jan. 31, 2017 USD ($)
Disaggregation of Revenue [Line Items]
Number of reportable segments | Divisions																		3
Net sales		$ 88,022		$ 104,833		$ 102,684		$ 111,129		$ 95,823		$ 101,349		$ 86,610		$ 93,535		$ 406,668	[3],[4]	$ 377,317	[3],[4]	$ 277,395	[4]
ELIM
Disaggregation of Revenue [Line Items]
Net sales																		(522)		(584)		(790)
ATD
Disaggregation of Revenue [Line Items]
Net sales																		129,749		124,688		105,217
EFD
Disaggregation of Revenue [Line Items]
Net sales																		226,574		213,298		138,855
AERO
Disaggregation of Revenue [Line Items]
Net sales																		50,867		39,915		34,113
All Segments
Disaggregation of Revenue [Line Items]
Net sales																		406,668		377,317		277,395
Domestic
Disaggregation of Revenue [Line Items]
Net sales																		358,339		335,761		241,867
Lighter-than-Air | Domestic
Disaggregation of Revenue [Line Items]
Net sales																		37,866		24,956		17,117
Lighter-than-Air | Domestic | AERO
Disaggregation of Revenue [Line Items]
Net sales																		37,866		24,956		17,117
Lighter-than-Air | International
Disaggregation of Revenue [Line Items]
Net sales																		932		93		357
Lighter-than-Air | International | AERO
Disaggregation of Revenue [Line Items]
Net sales																		932		93		357
Plastic Films & Sheeting | Domestic
Disaggregation of Revenue [Line Items]
Net sales																		208,370		200,746		131,915
Plastic Films & Sheeting | Domestic | ELIM
Disaggregation of Revenue [Line Items]
Net sales	[5]																	(512)		(584)		(789)
Plastic Films & Sheeting | Domestic | EFD
Disaggregation of Revenue [Line Items]
Net sales																		208,882		201,330		132,704
Plastic Films & Sheeting | International
Disaggregation of Revenue [Line Items]
Net sales																		17,692		11,968		6,151
Plastic Films & Sheeting | International | EFD
Disaggregation of Revenue [Line Items]
Net sales																		17,692		11,968		6,151
Precision Agriculture Equipment | Domestic
Disaggregation of Revenue [Line Items]
Net sales																		100,041		95,249		76,204
Precision Agriculture Equipment | Domestic | ELIM
Disaggregation of Revenue [Line Items]
Net sales																		(10)				(1)
Precision Agriculture Equipment | Domestic | ATD
Disaggregation of Revenue [Line Items]
Net sales																		100,051		95,249		76,205
Precision Agriculture Equipment | International
Disaggregation of Revenue [Line Items]
Net sales																		29,698		29,439		29,012
Precision Agriculture Equipment | International | ATD
Disaggregation of Revenue [Line Items]
Net sales																		29,698		29,439		29,012
Other | Domestic
Disaggregation of Revenue [Line Items]
Net sales																		12,062		14,810		16,631
Other | Domestic | AERO
Disaggregation of Revenue [Line Items]
Net sales																		12,062		14,810		16,631
Other | International
Disaggregation of Revenue [Line Items]
Net sales																		7		56		8
Other | International | AERO
Disaggregation of Revenue [Line Items]
Net sales																		$ 7		$ 56		$ 8

[1] In the third and fourth quarter of fiscal year 2018 hurricane recovery film net sales were $8,424 and $15,801, respectively. Sales of hurricane recovery film in fiscal year 2019 were $8,919, $1,510 and $4,065 for the first, third, and fourth quarters, respectively.

[2] In September of fiscal year 2018, the Company acquired CLI. For the first seven months of fiscal 2019 CLI contributed a total of $21,568 in sales and for the first seven months of fiscal 2018 the division generated $4,109 in sales to CLI as a customer.

[3] In September of fiscal year 2018, the Company acquired CLI. For the first seven months of fiscal 2019 CLI contributed a total of $21,568 in sales and for the first seven months of fiscal 2018 the division generated $4,109 in sales to CLI as a customer. Additionally, sales of hurricane recovery film in fiscal years 2019 and 2018 were $14,494 and $24,225, respectively

[4] Aerostar divested its client private business in the first quarter of fiscal 2019. Net sales from the client private business were $283, $5,592, and $5,886 in fiscal years 2019, 2018 and 2017, respectively. Operating profits for the client private business were not material for these periods.

[5] Intersegment sales for fiscal years 2019, 2018 and 2017 were primarily sales from Engineered Films to Aerostar.