Restructuring Charges (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Dec. 31, 2016 USD ($) employee	Dec. 31, 2015 USD ($)	Dec. 31, 2014 employee	Dec. 31, 2016 USD ($) employee	Dec. 31, 2015 USD ($)
Restructuring Charges
Document Period End Date				Dec. 31, 2016
Restructuring charges	$ (369)	$ 1,714		$ 4,317	$ 3,561
Reconciliation of restructuring liability
Costs charged to expense	(369)	1,714		4,317	3,561
Employee Severance
Restructuring Charges
Restructuring charges	$ (215)	795		$ 1,864	1,905
Expected number of positions eliminated | employee			50
Number of positions eliminated, inception to date | employee	24			24
Reconciliation of restructuring liability
Beginning of period	$ 2,101	2,279		$ 976	7,239
Costs charged to expense	(215)	795		1,864	1,905
Costs paid or settled	(579)	(1,209)		(1,510)	(7,492)
Change in foreign exchange	(46)	(43)		(69)	170
End of period	1,261	1,822		1,261	1,822
Employee Severance | Tennessee
Restructuring Charges
Restructuring charges				400
Reconciliation of restructuring liability
Costs charged to expense				400
Employee Severance | Mexico | Solid Capacitors
Restructuring Charges
Restructuring charges		100		300	900
Reconciliation of restructuring liability
Costs charged to expense		100		300	900
Employee Severance | Mexico | K-Salt
Restructuring Charges
Restructuring charges				100
Reconciliation of restructuring liability
Costs charged to expense				100
Employee Severance | Victoria Mexico [Member] | Solid Capacitors
Restructuring Charges
Restructuring charges		500
Reconciliation of restructuring liability
Costs charged to expense		500
Employee Severance | Florida
Restructuring Charges
Restructuring charges				300
Reconciliation of restructuring liability
Costs charged to expense				300
Employee Severance | England
Restructuring Charges
Restructuring charges				200
Reconciliation of restructuring liability
Costs charged to expense				200
Employee Severance | Sweden
Restructuring Charges
Restructuring charges				300
Reconciliation of restructuring liability
Costs charged to expense				300
Employee Severance | Europe
Restructuring Charges
Restructuring charges				300	400
Reconciliation of restructuring liability
Costs charged to expense				300	400
Employee Severance | Italy
Restructuring Charges
Restructuring accrual adjustment					(1,200)
Employee Severance | Europe and North America
Restructuring Charges
Restructuring charges		100			600
Reconciliation of restructuring liability
Costs charged to expense		100			600
Employee Severance | China | Film and Electrolytic
Restructuring Charges
Restructuring charges					600
Reconciliation of restructuring liability
Costs charged to expense					600
Manufacturing Relocation
Restructuring Charges
Restructuring charges	(154)	919		2,453	1,656
Reconciliation of restructuring liability
Beginning of period	1,982	0		0	0
Costs charged to expense	(154)	919		2,453	1,656
Costs paid or settled	(832)	(919)		(1,457)	(1,656)
Change in foreign exchange	0	0		0	0
End of period	996	$ 0		996	$ 0
Manufacturing Relocation | Film and Electrolytic
Restructuring Charges
Restructuring charges	100			400
Reconciliation of restructuring liability
Costs charged to expense	100			400
Manufacturing Relocation | Tennessee
Restructuring Charges
Restructuring charges				1,900
Restructuring accrual adjustment	(300)
Reconciliation of restructuring liability
Costs charged to expense				1,900
Manufacturing Relocation | Mexico | K-Salt
Restructuring Charges
Restructuring charges	100			100
Reconciliation of restructuring liability
Costs charged to expense	$ 100			100
Manufacturing Relocation | South Carolina
Restructuring Charges
Restructuring charges				100
Reconciliation of restructuring liability
Costs charged to expense				$ 100