Segment and Geographic Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
Dec. 31, 2017 USD ($) manufacturing_site	Dec. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) manufacturing_site business_group	Dec. 31, 2016 USD ($)
Segment and geographic information
Number of business groups \| business_group			3
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	$ 306,408	$ 188,029	$ 881,879	$ 560,272
Operating income (loss)	32,077	14,182	91,504	26,854
Depreciation and amortization expense	11,125	9,095	36,694	27,971
Restructuring charges (credits)	3,530	(369)	6,536	4,317
North and South America (“Americas”)
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	65,097	54,976	191,428	166,858
Europe, Middle East, Africa (“EMEA”)
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	68,676	55,765	201,711	176,298
Japan and Korea (“JPKO”)
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	48,395	0	128,514	0
Asia and Pacific Rim (“APAC”)
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	124,240	77,288	360,226	217,116
Operating Income (Loss) [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Restructuring charges (credits)	3,530	(369)	6,536	4,317
Corporate, Non-Segment [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating income (loss)	(39,420)	(25,600)	(101,156)	(75,291)
Depreciation and amortization expense	2,203	1,457	6,569	4,217
Corporate, Non-Segment [Member] \| Operating Income (Loss) [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Restructuring charges (credits)	$ 1,100	2	$ 3,121	330
Solid Capacitors
Segment and geographic information
Number of Manufacturing Sites \| manufacturing_site	11		11
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	$ 195,049	141,555	$ 568,435	426,140
Operating income (loss)	60,991	37,421	170,417	108,262
Depreciation and amortization expense	6,900	5,078	21,490	15,643
Write down of Long-lived Assets			2,100
Solid Capacitors \| Operating Income (Loss) [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Restructuring charges (credits)	$ 121	(128)	$ 841	566
Film and Electrolytic [Member]
Segment and geographic information
Number of Manufacturing Sites \| manufacturing_site	9		9
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	$ 51,300	46,474	$ 146,738	134,132
Operating income (loss)	574	2,361	4,188	(6,117)
Depreciation and amortization expense	2,500	2,560	7,609	8,111
Write down of Long-lived Assets			4,100
Film and Electrolytic [Member] \| Operating Income (Loss) [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Restructuring charges (credits)	$ 2,309	(243)	$ 2,574	3,421
Electro-magnetic, Sensors & Actuators [Member]
Segment and geographic information
Number of Manufacturing Sites \| manufacturing_site	4		4
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	$ 60,059	0	$ 166,706	0
Operating income (loss)	9,932	0	18,055	0
Depreciation and amortization expense	(478)	0	1,026	0
Electro-magnetic, Sensors & Actuators [Member] \| Operating Income (Loss) [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Restructuring charges (credits)	$ 0	$ 0	$ 0	$ 0

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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