Investment in NEC TOKIN (Details 2) - NECTOKIN - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Summarized financial information
Current assets	$ 240,427	$ 223,495
Noncurrent assets	260,614	273,785
Current liabilities	179,360	143,523
Noncurrent liabilities	335,500	296,873
Net sales	458,032	487,282	$ 490,369
Gross profit	98,709	103,773	86,227
Net income (loss)	$ (42,995)	$ (24,091)	$ (42,937)