Restructuring Charges (Details) (USD $)	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Restructuring Charges
Restructuring charges	$ 1,687,000	$ 1,364,000	$ 3,517,000	$ 5,974,000
Other restructuring costs		500,000	300,000	1,100,000
Reconciliation of restructuring liability
Costs charged to expense	1,687,000	1,364,000	3,517,000	5,974,000
Solid Capacitors
Restructuring Charges
Restructuring charges	169,000	99,000	1,399,000	3,145,000
Reconciliation of restructuring liability
Costs charged to expense	169,000	99,000	1,399,000	3,145,000
Manufacturing relocation costs
Restructuring Charges
Restructuring charges	539,000	548,000	2,223,000	1,023,000
Reconciliation of restructuring liability
Beginning of period	0	0	0	567,000
Costs charged to expense	539,000	548,000	2,223,000	1,023,000
Costs paid or settled	(539,000)	(548,000)	(2,223,000)	(1,590,000)
Change in foreign exchange	0	0	0	0
End of period	0	0	0	0
Manufacturing relocation costs | Landsberg Germany
Restructuring Charges
Restructuring charges	539,000		700,000
Reconciliation of restructuring liability
Costs charged to expense	539,000		700,000
Manufacturing relocation costs | Italy and Evora Portugal
Restructuring Charges
Restructuring charges		500,000		1,023,000
Reconciliation of restructuring liability
Costs charged to expense		500,000		1,023,000
Manufacturing relocation costs | Evora Portugal
Restructuring Charges
Restructuring charges			1,300,000
Reconciliation of restructuring liability
Costs charged to expense			1,300,000
Personnel reduction costs
Restructuring Charges
Restructuring charges	1,148,000	816,000	1,294,000	4,951,000
Reconciliation of restructuring liability
Beginning of period	3,384,000	8,947,000	6,217,000	13,509,000
Costs charged to expense	1,148,000	816,000	1,294,000	4,951,000
Costs paid or settled	(1,264,000)	(4,648,000)	(4,187,000)	(13,517,000)
Change in foreign exchange	(241,000)	155,000	(297,000)	327,000
End of period	3,027,000	5,270,000	3,027,000	5,270,000
Personnel reduction costs | Innovation center
Restructuring Charges
Restructuring charges				1,900,000
Reconciliation of restructuring liability
Costs charged to expense				1,900,000
Personnel reduction costs | Europe
Restructuring Charges
Restructuring charges	1,148,000		1,000,000
Reconciliation of restructuring liability
Costs charged to expense	1,148,000		1,000,000
Personnel reduction costs | Weymouth United Kingdom
Restructuring Charges
Restructuring charges		300,000		400,000
Reconciliation of restructuring liability
Costs charged to expense		300,000		400,000
Personnel reduction costs | Mexican operations | Solid Capacitors
Restructuring Charges
Restructuring charges				1,200,000
Reconciliation of restructuring liability
Costs charged to expense				1,200,000
Personnel reduction costs | Italy | Cassia Integrazione Guadagni Straordinaria (CIGS) plan
Restructuring Charges
Restructuring charges				400,000
Reconciliation of restructuring liability
Costs charged to expense				$ 400,000
Personnel reduction costs | Italy | Cassia Integrazione Guadagni Straordinaria (CIGS) plan | Maximum
Restructuring Charges
Number of employees covered under CIGS plan				170
Term of CIGS plan				12 months