Restructuring Charges (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Restructuring Charges
Restructuring charges	$ (96)	$ 1,613
Reconciliation of restructuring liability
Costs charged to expense	$ (96)	$ 1,613
Employee Severance
Restructuring Charges
Business Acquisition, Planned Restructuring Activities, Description	0	0
Restructuring charges	$ (79)	$ 238
Reconciliation of restructuring liability
Beginning of period	9,629	999
Costs charged to expense	(79)	238
Costs paid or settled	(5,136)	(457)
Change in foreign exchange	(244)	18
End of period	4,170	$ 798
Employee Severance | Corporate, Non-Segment [Member]
Restructuring Charges
Restructuring and Related Cost, Incurred Cost	(79)
Restructuring and Related Cost, Cost Incurred to Date	2,655
Restructuring and Related Cost, Expected Cost	2,655
Employee Severance | Solid Capacitors
Restructuring Charges
Restructuring and Related Cost, Incurred Cost	0
Restructuring and Related Cost, Cost Incurred to Date	0
Restructuring and Related Cost, Expected Cost	897
Manufacturing Relocation 1 [Member]
Reconciliation of restructuring liability
Costs paid or settled	0
Facility Closing [Member] | Corporate, Non-Segment [Member]
Restructuring Charges
Restructuring and Related Cost, Incurred Cost	0
Restructuring and Related Cost, Cost Incurred to Date	909
Restructuring and Related Cost, Expected Cost	909
Facility Closing [Member] | Solid Capacitors
Restructuring Charges
Restructuring and Related Cost, Incurred Cost	0
Restructuring and Related Cost, Cost Incurred to Date	0
Restructuring and Related Cost, Expected Cost	$ 2,098
Manufacturing Relocation
Restructuring Charges
Business Acquisition, Planned Restructuring Activities, Description		314
Restructuring charges	$ 0	$ 1,375
Reconciliation of restructuring liability
Beginning of period	330	406
Costs charged to expense	0	1,375
Costs paid or settled		(1,781)
Change in foreign exchange	(13)	0
End of period	$ 317	314
Manufacturing Relocation | FLORIDA
Restructuring Charges
Restructuring charges		900
Reconciliation of restructuring liability
Costs charged to expense		900
Manufacturing Relocation | Tennessee
Restructuring Charges
Restructuring charges		200
Reconciliation of restructuring liability
Costs charged to expense		200
Manufacturing Relocation | Mexico | K-Salt
Restructuring Charges
Restructuring charges		200
Reconciliation of restructuring liability
Costs charged to expense		200
Manufacturing Relocation | Victoria Mexico [Member] | Solid Capacitors
Restructuring Charges
Restructuring accrual adjustment		$ 100