Business Segments and Major Customer Information - Segment reporting information (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended	12 Months Ended
		Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2015	Jan. 31, 2017		Jan. 31, 2016		Jan. 31, 2015
Segment Reporting Information [Line Items]
Sales					$ 277,395		$ 258,229		$ 378,153
Operating income(e)					28,413		4,391		43,801
Assets					301,509		298,688		362,873
Capital expenditures					4,796		13,046		17,041
Depreciation and amortization					15,436		17,136		17,369
Goodwill impairment loss					0		11,497		0
Impairment of Long-Lived Assets Held-for-use					87		3,826		0
Applied Technology [Member]
Segment Reporting Information [Line Items]
Goodwill impairment loss							0
Engineered Films [Member]
Segment Reporting Information [Line Items]
Goodwill impairment loss							0
Corporate & Other [Member]
Segment Reporting Information [Line Items]
Operating income(e)	[1]				(19,624)		(17,110)		(21,704)
Assets	[2]				76,843	[3]	65,624	[3]	74,960
Capital expenditures					464		661		2,523
Depreciation and amortization					1,308		1,676		2,230
Vista Reporting Unit [Member]
Segment Reporting Information [Line Items]
Goodwill impairment loss							11,497
Impairment of Long-Lived Assets Held-for-use			$ 3,813	$ 3,813			3,826		0
Aerostar [Member]
Segment Reporting Information [Line Items]
Goodwill impairment loss							0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales					277,395		258,229		378,153
Operating income(e)	[1]				48,037		21,501		65,505
Assets					224,666		233,064		287,913
Capital expenditures					4,332		12,385		14,518
Depreciation and amortization					14,128		15,460		15,139
Operating Segments [Member] | Applied Technology [Member]
Segment Reporting Information [Line Items]
Sales					105,217		92,599		142,154
Operating income(e)					26,643	[4]	18,319	[1],[5]	34,557	[5]
Assets					67,911	[3]	65,490	[3]	88,764
Capital expenditures					1,017		664		3,478
Depreciation and amortization					3,828		4,428		5,569
Gain on disposal of assets					160		611
Operating Segments [Member] | Engineered Films [Member]
Segment Reporting Information [Line Items]
Sales					138,855		129,465		166,634
Operating income(e)	[1]				22,966		17,892		21,802
Assets					133,309	[3]	134,942	[3]	140,023
Capital expenditures					2,768		10,780		8,241
Depreciation and amortization					8,580		7,735		6,096
Operating Segments [Member] | Vista Reporting Unit [Member]
Segment Reporting Information [Line Items]
Pre-contract deferred costs written off							2,933
Goodwill impairment loss							11,497
Operating Segments [Member] | Aerostar [Member]
Segment Reporting Information [Line Items]
Sales					34,113		36,368		80,772
Operating income(e)	[1]				(1,560)	[6]	(14,801)	[7]	8,983
Assets					23,515	[3]	32,689	[3]	59,274
Capital expenditures					547		941		2,799
Depreciation and amortization					1,720		3,297		3,474
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating income(e)	[1]				(12)		91		163
Assets					(69)		(57)		(148)
Intersegment Eliminations [Member] | Applied Technology [Member]
Segment Reporting Information [Line Items]
Sales					(1)		(8)		(231)
Intersegment Eliminations [Member] | Engineered Films [Member]
Segment Reporting Information [Line Items]
Sales					(789)		(195)		(652)
Intersegment Eliminations [Member] | Aerostar [Member]
Segment Reporting Information [Line Items]
Sales					0		0		(10,524)
Cost of Sales [Member] | Vista Research [Member]
Segment Reporting Information [Line Items]
Pre-contract deferred costs written off			$ 2,933	2,933	0		2,933		0
Cost of Sales [Member] | Radar Inventory [Member] | Vista Research [Member]
Segment Reporting Information [Line Items]
Inventory Write-down		$ 2,278		2,278	$ 2,278		0		$ 0
Vista Research [Member] | Cost of Sales [Member]
Segment Reporting Information [Line Items]
Reduction in fair value of contingent consideration liability				$ 2,273			$ 2,273

[1] 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.

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

[3] Certain facilities owned by the Company are shared by more than one reporting segment. Beginning with fiscal year 2016 all facilities are reported as an asset based on the segment that acquired the asset as we believe this better reflects total assets of the business segment. In prior fiscal years (which have not been recast in this table), the book value of certain shared facilities was allocated across reporting segments based on usage. 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.

[4] (e) At the segment level, operating income does not include an allocation of general and administrative expenses.

[5] The fiscal year ended January 31, 2016 includes gains of $611 on disposal of assets related to the exit of contract manufacturing operations.

[6] The fiscal year 2017 includes inventory write-downs of $2,278 for Vista as a result of discontinuing sales activities for a specific radar product line within its business.

[7] The fiscal year ended January 31, 2016 includes pre-contract cost write-offs of $2,933, a goodwill impairment loss of $11,497, a long-lived asset impairment loss of $3,826, and a $2,273 reduction of an acquisition-related contingent liability for Vista as a result of lower financial expectations for net sales and operating income.