Segment and Geographic Information (Details) (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 business_group	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting [Abstract]
Number of business groups									2
Segment and geographic information
Net sales	$ 215,821	$ 207,339	$ 208,449	$ 202,057	$ 199,539	$ 197,697	$ 211,165	$ 215,500	$ 833,666	$ 823,903	$ 924,052
Operating income (loss)	(5,207)	3,623	1,585	(18,212)	(14,448)	(3,437)	(12,872)	(4,323)	(18,211)	(35,080)	28,083
Depreciation and amortization									49,527	45,158	43,401
Capital expenditures									32,147	46,174	49,314
Restructuring charges									14,122	18,719	14,254
Impairment and write-down of long-lived assets									4,476	8,674	15,786
Net (gain) loss on sales and disposals of assets									32	18	318
Assets	843,667				911,591				843,667	911,591
Solid Capacitors
Segment and geographic information
Number of manufacturing sites									9
Net sales									626,494	622,305	630,762
Operating income (loss)									91,848	94,986	111,769
Depreciation and amortization									28,081	27,407	27,939
Capital expenditures									10,498	16,838	19,039
Restructuring charges									8,108	7,335	1,161
Impairment and write-down of long-lived assets									3,920	3,348	15,786
Net (gain) loss on sales and disposals of assets									(705)	(161)	338
Assets	479,377				525,270				479,377	525,270
Film and Electrolytic
Segment and geographic information
Number of manufacturing sites									12
Net sales									207,172	201,598	293,290
Operating income (loss)									(17,587)	(31,109)	12,347
Depreciation and amortization									14,557	13,360	11,398
Capital expenditures									14,494	23,970	21,539
Restructuring charges									5,657	9,621	13,093
Impairment and write-down of long-lived assets									556	5,326	0
Net (gain) loss on sales and disposals of assets									767	179	(20)
Assets	287,861				300,501				287,861	300,501
Corporate
Segment and geographic information
Operating income (loss)									(92,472)	(98,957)	(96,033)
Depreciation and amortization									6,889	4,391	4,064
Capital expenditures									7,155	5,366	8,736
Restructuring charges									357	1,763	0
Net (gain) loss on sales and disposals of assets									(30)	0	0
Assets	$ 76,429				$ 85,820				$ 76,429	$ 85,820