Goodwill and Intangible Assets - Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Goodwill [Line Items]
Goodwill	$ (40,294)	$ (35,584)
Solid Capacitors
Goodwill [Line Items]
Goodwill	35,584	35,584
Accumulated impairment losses	0	0
Goodwill	(35,584)	(35,584)
Film and Electrolytic
Goodwill [Line Items]
Goodwill	1,092	1,092
Accumulated impairment losses	(1,092)	(1,092)
Goodwill	0	$ 0
Corporate
Goodwill [Line Items]
Goodwill	4,710
Goodwill	(4,710)
Goodwill, Acquired During Period	$ 4,710