Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Revenues [Abstract]
Net sales	$ 188,029		$ 177,184	$ 560,272	$ 550,897
Operating costs and expenses:
Cost of sales	140,692		138,436	423,999	429,630
Selling, general and administrative expenses	26,665		22,278	78,551	75,656
Research and development	7,059		6,134	21,107	18,560
Restructuring charges	(369)		1,714	4,317	3,561
Write down of long-lived assets	0	$ 6,200	0	6,193	0
Net (gain) loss on sales and disposals of assets	132		129	307	(233)
Total operating costs and expenses	174,179		168,691	534,474	527,174
Operating income (loss)	13,850		8,493	25,798	23,723
Non-operating (income) expense:
Interest income	(5)		(4)	(14)	(10)
Interest expense	9,918		9,852	29,751	29,676
Change in value of NEC TOKIN option	(6,900)		(700)	3,500	26,300
Other (income) expense, net	(3,384)		(1,320)	(6,683)	(2,495)
Income (loss) from before income taxes and equity income (loss) from NEC TOKIN	14,221		665	(756)	(29,748)
Income tax expense (benefit)	1,810		2,760	4,440	3,950
Income (loss) before equity income (loss) from NEC TOKIN	12,411		(2,095)	(5,196)	(33,698)
Equity income (loss) from NEC TOKIN	(133)		(6,505)	271	(4,758)
Net income (loss)	$ 12,278		$ (8,600)	$ (4,925)	$ (38,456)
Net income (loss) per basic share:
Net income (loss) per basic share (in usd per share)	$ 0.26		$ (0.19)	$ (0.11)	$ (0.84)
Net income (loss) per diluted share (in usd per share)	$ 0.22		$ (0.19)	$ (0.11)	$ (0.84)
Weighted-average shares outstanding:
Basic (in shares)	46,606		46,081	46,469	45,953
Diluted (in shares)	55,296		46,081	46,469	45,953