Represents the number of manufacturing sites operated by the entity.

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- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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- Definition

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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- Definition

Amount, before tax, of (gain) loss recognized for the (reversal of write-down) write-down to fair value, less cost to sell, of a disposal group. Excludes discontinued operations.

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- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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- Definition

The net result for the period of deducting operating expenses from operating revenues.

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No definition available.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Segment and Geographic Information - Narrative (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2020 USD ($) manufacturing_site	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2020 USD ($) business_group manufacturing_site	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)
Segment Reporting [Abstract]
Number of business groups \| business_group									3
Segment and geographic information
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down									$ 19,710	$ 1,660	$ (992)
Assets	$ 1,393,097				$ 1,318,095				1,393,097	1,318,095
Operating income (loss)	11,728	$ 28,648	$ 49,090	$ 58,400	54,057	$ 61,616	$ 50,000	$ 35,176	147,866	200,849	112,852
Depreciation and amortization									62,819	52,628	50,661
Solid Capacitors
Segment and geographic information
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down									1,538	235	689
Assets	$ 888,046				794,402				$ 888,046	794,402
Number of manufacturing sites \| manufacturing_site	9								9
Operating income (loss)									$ 345,245	348,150	234,473
Depreciation and amortization									33,462	28,795	27,329
Film and Electrolytic
Segment and geographic information
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down									7,780	(93)	(3,356)
Assets	$ 207,601				219,711				$ 207,601	219,711
Number of manufacturing sites \| manufacturing_site	8								8
Operating income (loss)									$ (14,209)	8,183	3,622
Depreciation and amortization									10,142	9,763	10,918
Electro-magnetic, Sensors & Actuators [Member]
Segment and geographic information
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down									0	0	1,272
Assets	$ 220,107				234,419				$ 220,107	234,419
Number of manufacturing sites \| manufacturing_site	4								4
Operating income (loss)									$ 13,101	22,546	15,694
Depreciation and amortization									7,379	5,226	4,407
Corporate
Segment and geographic information
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down									10,392	1,518	403
Assets	$ 77,343				$ 69,563				77,343	69,563
Operating income (loss)									(196,271)	(178,030)	(140,937)
Depreciation and amortization									$ 11,836	$ 8,844	$ 8,007