Segment and Geographic Information - Net Sales by Country (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales	$ 183,926	$ 177,184	$ 186,123	$ 187,590	$ 193,708	$ 201,310	$ 215,293	$ 212,881	$ 734,823	$ 823,192	$ 833,666
Property, plant and equipment, net	241,839				249,641				241,839	249,641
Solid Capacitors
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									556,303	621,275	626,494
Film and Electrolytic
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									$ 178,520	201,917	207,172
Net sales | Sales risk
Net sales and property, plant and equipment, goodwill, intangible assets
Concentration Risk, Customer									1
Net sales									$ 99,300	124,400	128,400
Net sales | Sales risk | Solid Capacitors
Net sales and property, plant and equipment, goodwill, intangible assets
Concentration Risk, Customer									1
Net sales									$ 85,300	109,100	115,500
Net sales | Sales risk | Film and Electrolytic
Net sales and property, plant and equipment, goodwill, intangible assets
Concentration Risk, Customer									1
Net sales									$ 14,000	15,300	12,900
Net sales | Geographic risk
Net sales and property, plant and equipment, goodwill, intangible assets
Threshold for Disclosure Percentage									3.00%
Property, Plant and Equipment [Member] | Geographic risk
Net sales and property, plant and equipment, goodwill, intangible assets
Threshold for Disclosure Percentage									2.77608%
INDONESIA
Net sales and property, plant and equipment, goodwill, intangible assets
Property, plant and equipment, net	4,556				5,335				$ 4,556	5,335
FINLAND
Net sales and property, plant and equipment, goodwill, intangible assets
Property, plant and equipment, net	989				1,439				989	1,439
United States
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									201,878	238,840	245,032
Property, plant and equipment, net	54,658				59,754				54,658	59,754
Hong Kong
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									133,117	131,109	135,570
Germany
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									83,589	107,859	105,261
Europe [Member]
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									57,362	58,879	70,895
China
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									65,043	65,289	67,460
Property, plant and equipment, net	26,705				29,871				26,705	29,871
Asia Pacific [Member]
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									61,414	62,864	51,467
United Kingdom
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									28,083	32,127	36,085
Netherlands
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									31,218	38,853	33,581
Singapore
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									16,260	22,516	27,777
Italy
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									14,391	19,013	20,249
Property, plant and equipment, net	44,699				44,595				44,699	44,595
Hungary
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									17,766	22,745	18,332
Mexico
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									23,041	21,164	17,886
Property, plant and equipment, net	61,859				66,120				61,859	66,120
Other (1)
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									1,661	1,934	$ 4,071
Property, plant and equipment, net	10,793				11,449				10,793	11,449
PORTUGAL
Net sales and property, plant and equipment, goodwill, intangible assets
Property, plant and equipment, net	23,449				17,352				23,449	17,352
MACEDONIA, THE FORMER YUGOSLAV REPUBLIC OF
Net sales and property, plant and equipment, goodwill, intangible assets
Property, plant and equipment, net	$ 14,131				$ 13,726				$ 14,131	$ 13,726
Minimum | Net sales | Sales risk
Net sales and property, plant and equipment, goodwill, intangible assets
Concentration risk, percentage									0.00%
Minimum | Net sales | Sales risk | Solid Capacitors
Net sales and property, plant and equipment, goodwill, intangible assets
Concentration risk, percentage									0.00%
Minimum | Net sales | Sales risk | Film and Electrolytic
Net sales and property, plant and equipment, goodwill, intangible assets
Concentration risk, percentage									0.00%