Equity Method Investments Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 11,212	$ 12,016
Novasentis [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	15.00%
Equity Method Investments	$ 2,546	2,870
Nippon Yttrium Co., Ltd (NYC) [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	30.00%
Equity Method Investments	$ 7,612	8,148
NT Sales Co., Ltd (NTS) [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	33.00%
Equity Method Investments	$ 1,054	$ 998
NT Sales Co., Ltd (NTS) [Member] \| TOKIN [Member] \| Discontinued Operations, Disposed of by Sale [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	67.00%

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66022249&loc=d3e33749-111570

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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