Segment and Geographic Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales	$ 215,821	$ 207,339	$ 208,449	$ 202,057	$ 199,539	$ 197,697	$ 211,165	$ 215,500	$ 833,666	$ 823,903	$ 924,052
Property, plant and equipment, net	292,648				303,682				292,648	303,682
Solid Capacitors
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									626,494	622,305	630,762
Film and Electrolytic
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									207,172	201,598	293,290
Net sales | Sales risk
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									128,400	127,700	125,300
Number of customers whose accounts receivable balances exceeded 10% of gross accounts receivable									1	1	1
Net sales | Sales risk | Solid Capacitors
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									115,500	119,000	112,300
Number of customers whose accounts receivable balances exceeded 10% of gross accounts receivable									1	1	1
Net sales | Sales risk | Film and Electrolytic
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									12,900	8,700	13,000
Number of customers whose accounts receivable balances exceeded 10% of gross accounts receivable									1	1	1
Net sales | Geographic risk
Net sales and property, plant and equipment, goodwill, intangible assets
Disclosure threshold (as a percent)									2.00%	2.00%	2.00%
United States
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									245,032	228,975	219,785
Property, plant and equipment, net	64,754				71,447				64,754	71,447
Hong Kong
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									135,570	148,014	147,054
Germany
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									105,261	105,818	138,700
Europe
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									70,895	82,021	133,378
China
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									67,460	70,696	79,681
Property, plant and equipment, net	31,405				33,873				31,405	33,873
Asia Pacific
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									51,467	50,735	43,433
Portugal
Net sales and property, plant and equipment, goodwill, intangible assets
Property, plant and equipment, net	23,817				28,716				23,817	28,716
Macedonia
Net sales and property, plant and equipment, goodwill, intangible assets
Property, plant and equipment, net	21,044				18,724				21,044	18,724
Indonesia
Net sales and property, plant and equipment, goodwill, intangible assets
Property, plant and equipment, net	6,026				7,243				6,026	7,243
Finland
Net sales and property, plant and equipment, goodwill, intangible assets
Property, plant and equipment, net	2,280				2,435				2,280	2,435
United Kingdom
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									36,085	34,188	39,512
Property, plant and equipment, net	492				5,246				492	5,246
Netherlands
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									33,581	24,568	19,447
Singapore
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									27,777	25,060	33,586
Italy
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									20,249	21,203	31,064
Property, plant and equipment, net	61,726				51,800				61,726	51,800
Hungary
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									18,332	13,554	16,206
Mexico
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									17,886	15,923	16,944
Property, plant and equipment, net	67,154				69,870				67,154	69,870
Other
Net sales and property, plant and equipment, goodwill, intangible assets
Net sales									4,071	3,148	5,262
Property, plant and equipment, net	$ 13,950				$ 14,328				$ 13,950	$ 14,328