Segment and Geographic Information - Narrative (Details)	12 Months Ended
	Mar. 31, 2017 USD ($) business_group manufacturing_site	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)
Segment Reporting [Abstract]
Number of business groups | business_group	2
Segment and geographic information
Write down of long-lived assets | $	$ 10,279,000	$ 0	$ 0
Solid Capacitors
Segment and geographic information
Write down of long-lived assets | $	$ 2,076,000
Number of manufacturing sites | manufacturing_site	9
Film and Electrolytic
Segment and geographic information
Number of manufacturing sites | manufacturing_site	9