Segment and Geographic Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) business_group manufacturing_site	Sep. 30, 2015 USD ($)
Segment and geographic information
Number of business groups | business_group			2
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	$ 187,308	$ 186,123	$ 372,243	$ 373,713
Operating income (loss)	3,050	13,987	11,948	15,230
Depreciation and amortization expense	9,440	9,265	18,876	19,182
Restructuring charges	3,998	23	4,686	1,847
Write down of Long-lived Assets	6,193	0	6,193	0
North and South America (“Americas”)
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	56,781	58,080	111,882	114,114
Europe, Middle East, Africa (“EMEA”)
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	60,047	59,458	120,533	121,015
Asia and Pacific Rim (“APAC”)
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	70,480	68,585	139,828	138,584
Operating Income (Loss) [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Restructuring charges	3,998	23	4,686	1,847
Write down of Long-lived Assets	6,193	0	6,193	0
Corporate, Non-Segment [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating income (loss)	(25,264)	(22,209)	(49,978)	(51,711)
Depreciation and amortization expense	1,457	1,159	2,760	2,378
Corporate, Non-Segment [Member] | Operating Income (Loss) [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Restructuring charges	325	202	328	508
Write down of Long-lived Assets	0	0	$ 0	0
Solid Capacitors
Segment and geographic information
Number of Manufacturing Sites | manufacturing_site			9
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	142,641	141,284	$ 284,585	280,961
Operating income (loss)	35,410	33,979	70,489	64,012
Depreciation and amortization expense	5,147	5,178	10,565	10,934
Write down of Long-lived Assets	2,100
Solid Capacitors | Operating Income (Loss) [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Restructuring charges	558	570	694	802
Write down of Long-lived Assets	2,076	0	$ 2,076	0
Film and Electrolytic
Segment and geographic information
Number of Manufacturing Sites | manufacturing_site			10
Segment Reporting Information, Profit (Loss) [Abstract]
Net sales	44,667	44,839	$ 87,658	92,752
Operating income (loss)	(7,096)	2,217	(8,563)	2,929
Depreciation and amortization expense	2,836	2,928	5,551	5,870
Write down of Long-lived Assets	4,100
Film and Electrolytic | Operating Income (Loss) [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Restructuring charges	3,115	(749)	3,664	537
Write down of Long-lived Assets	$ 4,117	$ 0	$ 4,117	$ 0