Business Segments and Major Customer Information - Segment Reporting Information (Details) - USD ($)		3 Months Ended																	7 Months Ended		12 Months Ended
		Jan. 31, 2019		Oct. 31, 2018		Jul. 31, 2018		Apr. 30, 2018		Jan. 31, 2018		Oct. 31, 2017		Jul. 31, 2017		Apr. 30, 2017		Oct. 31, 2016	Aug. 31, 2018	Aug. 31, 2017	Jan. 31, 2019		Jan. 31, 2018		Jan. 31, 2017
Segment Reporting Information [Line Items]
Net sales		$ 88,022,000	[1]	$ 104,833,000	[1],[2]	$ 102,684,000	[2]	$ 111,129,000	[2]	$ 95,823,000	[1]	$ 101,349,000	[1],[2]	$ 86,610,000	[2]	$ 93,535,000	[2]				$ 406,668,000	[3],[4]	$ 377,317,000	[3],[4]	$ 277,395,000	[4]
Operating income(a)		3,361,000		13,612,000		$ 16,629,000		21,531,000	[5]	11,422,000		17,829,000		$ 11,700,000		$ 18,219,000					55,133,000	[6]	59,170,000	[6]	28,413,000	[7]
Assets(b)		360,245,000								326,803,000											360,245,000		326,803,000		301,509,000
Capital expenditures																					14,127,000		12,011,000		4,796,000
Depreciation and amortization																					15,123,000		14,802,000		15,436,000
Cost of Sales
Segment Reporting Information [Line Items]
Inventory write-down																					0		0		2,278,000
Applied Technology
Segment Reporting Information [Line Items]
Net sales																					129,749,000		124,688,000		105,217,000
Engineered Films
Segment Reporting Information [Line Items]
Net sales																					226,574,000		213,298,000		138,855,000
Engineered Films | Hurricane Recovery Film
Segment Reporting Information [Line Items]
Net sales		4,065,000		$ 1,510,000				8,919,000		15,801,000		$ 8,424,000									14,494,000		24,225,000
Engineered Films | CLI
Segment Reporting Information [Line Items]
Net sales																			$ 21,568,000	$ 4,109,000
Aerostar
Segment Reporting Information [Line Items]
Net sales																					50,867,000		39,915,000		34,113,000
Aerostar | Cost of Sales | Radar Inventory
Segment Reporting Information [Line Items]
Inventory write-down																		$ 2,278,000							2,278,000
Corporate & Other
Segment Reporting Information [Line Items]
Operating income(a)	[6],[8]																				(31,769,000)		(23,553,000)		(19,624,000)
Assets(b)	[9],[10]	99,500,000								72,704,000											99,500,000		72,704,000		76,843,000
Capital expenditures																					2,365,000		2,051,000		464,000
Depreciation and amortization																					1,650,000		1,290,000		1,308,000
Client Private Disposal Group | Aerostar
Segment Reporting Information [Line Items]
Net sales																					283,000		5,592,000		5,886,000
Operating Segments
Segment Reporting Information [Line Items]
Net sales	[4]																				406,668,000	[3]	377,317,000	[3]	277,395,000
Operating income(a)	[8]																				86,902,000		82,723,000		48,037,000	[7]
Assets(b)	[10]	260,745,000								254,099,000											260,745,000		254,099,000		224,666,000
Capital expenditures																					11,762,000		9,960,000		4,332,000
Depreciation and amortization																					13,473,000		13,512,000		14,128,000
Operating Segments | Applied Technology
Segment Reporting Information [Line Items]
Net sales																					129,749,000		124,688,000		105,217,000
Operating income(a)	[8]																				39,044,000		31,257,000		26,643,000
Assets(b)	[10]	79,742,000								66,555,000											79,742,000		66,555,000		67,911,000
Capital expenditures																					2,050,000		1,489,000		1,017,000
Depreciation and amortization																					3,433,000		3,365,000		3,828,000
Operating Segments | Engineered Films
Segment Reporting Information [Line Items]
Net sales																					226,574,000	[3]	213,298,000	[3]	138,855,000
Operating income(a)	[8]																				39,714,000		47,324,000		22,966,000
Assets(b)	[10]	159,592,000								168,797,000											159,592,000		168,797,000		133,309,000
Capital expenditures																					9,544,000		8,128,000		2,768,000
Depreciation and amortization																					9,149,000		8,761,000		8,580,000
Operating Segments | Aerostar
Segment Reporting Information [Line Items]
Net sales																					50,867,000	[4]	39,915,000		34,113,000	[4]
Operating income(a)	[8]																				8,179,000		4,122,000		(1,560,000)	[7]
Assets(b)		21,515,000	[8]							22,127,000	[10]										21,515,000	[8]	22,127,000	[10]	23,515,000	[10]
Capital expenditures																					168,000		343,000		547,000
Depreciation and amortization																					891,000		1,386,000		1,720,000
Intersegment Eliminations
Segment Reporting Information [Line Items]
Operating income(a)	[8]																				(35,000)		20,000		(12,000)
Assets(b)	[10]	$ (104,000)								$ (3,380,000)											(104,000)		(3,380,000)		(69,000)
Intersegment Eliminations | Applied Technology
Segment Reporting Information [Line Items]
Net sales																					(10,000)		0		(1,000)
Intersegment Eliminations | Engineered Films
Segment Reporting Information [Line Items]
Net sales																					(512,000)		(584,000)		$ (789,000)
Charitable Gift
Segment Reporting Information [Line Items]
Loss Contingency, Loss in Period								$ 4,503,000													4,503,000
Project Atlas
Segment Reporting Information [Line Items]
Other General and Administrative Expense																					$ 4,000,000		$ 900,000

[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] In the first quarter of fiscal 2019, the Company incurred a $4,503 operating expense related to the previously announced gift to SDSU.

[6] Fiscal 2019 administrative expenses included a $4,503 expense related to the previously announced gift to SDSU and approximately $4,000 of expenses related to Project Atlas. Project Atlas related expenses in fiscal 2018 were approximately $900.

[7] Fiscal year 2017 included inventory write-downs of $2,278 for Aerostar as a result of discontinuing sales activities for a specific radar product line within its business

[8] At the segment level, operating income does not include an allocation of general and administrative expenses and, as a result, general and administrative expenses are reported as "Operating (loss) from administrative expenses" in Corporate & Other.

[9] Assets are principally cash, investments, deferred taxes, and other receivables.

[10] Certain facilities owned by the Company are shared by more than one reporting segment. All facilities are reported as an asset based on the segment that acquired the asset as the Company believes this most appropriately reflects the total assets of each business segment. Expenses and costs related to these facilities, including depreciation expense, are allocated and reported in each reporting segment's operating income for each fiscal year presented.