Condensed Consolidating Financial Statements Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenues [Abstract]
Net sales	$ 187,308	$ 186,123	$ 372,243	$ 373,713
Operating costs and expenses:
Cost of sales	140,895	143,317	283,307	291,194
Selling, general and administrative expenses	25,972	22,948	51,886	53,378
Research and development	7,116	6,152	14,048	12,426
Restructuring charges	3,998	23	4,686	1,847
Write down of long-lived assets	6,193	0	6,193	0
Net (gain) loss on sales and disposals of assets	84	(304)	175	(362)
Total operating costs and expenses	184,258	172,136	360,295	358,483
Operating income (loss)	3,050	13,987	11,948	15,230
Interest income	(6)	(3)	(9)	(6)
Interest expense	9,910	9,811	19,833	19,824
Change in value of NEC TOKIN option	(1,600)	(2,200)	10,400	27,000
Other (income) expense, net	905	2,091	3,299	1,175
Equity in earnings of subsidiaries	0	0	0	0
Income (loss) from continuing operations before income taxes and equity income (loss) from NEC TOKIN	(4,349)	8,470	(14,977)	(30,413)
Income tax expense (benefit)	830	1,438	2,630	1,190
Income (loss) from continuing operations before equity income (loss) from NEC TOKIN	(5,179)	7,032	(17,607)	(31,603)
Equity income (loss) from NEC TOKIN	181	162	404	1,747
Net income (loss)	(4,998)	7,194	(17,203)	(29,856)
Reclassifications and Eliminations
Revenues [Abstract]
Net sales	(199,561)	(212,120)	(398,689)	(427,900)
Operating costs and expenses:
Cost of sales	(186,448)	(198,396)	(372,646)	(398,441)
Selling, general and administrative expenses	(13,114)	(13,724)	(26,044)	(29,459)
Research and development	0	0	0	0
Restructuring charges	0	0	0	0
Write down of long-lived assets	0		0
Net (gain) loss on sales and disposals of assets	0	0	0	0
Total operating costs and expenses	(199,562)	(212,120)	(398,690)	(427,900)
Operating income (loss)	1	0	1	0
Interest income	0	0	0	0
Interest expense	0	0	0	0
Change in value of NEC TOKIN option	0
Other (income) expense, net	0	0	0	0
Equity in earnings of subsidiaries	(5,481)	(17,679)	(3,836)	9,114
Income (loss) from continuing operations before income taxes and equity income (loss) from NEC TOKIN	(5,480)	(17,679)	(3,835)	9,114
Income tax expense (benefit)	0	0	0	0
Income (loss) from continuing operations before equity income (loss) from NEC TOKIN	(5,480)	(17,679)	(3,835)	9,114
Equity income (loss) from NEC TOKIN	0	0	0	0
Net income (loss)	(5,480)	(17,679)	(3,835)	9,114
Parent
Revenues [Abstract]
Net sales	0	0	0	0
Operating costs and expenses:
Cost of sales	489	521	766	699
Selling, general and administrative expenses	9,631	8,906	19,776	18,722
Research and development	91	66	156	(53)
Restructuring charges	0	0	0	0
Write down of long-lived assets	0		0
Net (gain) loss on sales and disposals of assets	(285)	(7)	(285)	(7)
Total operating costs and expenses	9,926	9,486	20,413	19,361
Operating income (loss)	(9,926)	(9,486)	(20,413)	(19,361)
Interest income	0	0	0	0
Interest expense	9,396	9,465	18,819	18,934
Change in value of NEC TOKIN option	0	0	0	0
Other (income) expense, net	8,843	8,466	18,193	17,553
Equity in earnings of subsidiaries	5,481	17,679	3,836	(9,114)
Income (loss) from continuing operations before income taxes and equity income (loss) from NEC TOKIN	(4,998)	7,194	(17,203)	(29,856)
Income tax expense (benefit)	0	0	0	0
Income (loss) from continuing operations before equity income (loss) from NEC TOKIN	(4,998)	7,194	(17,203)	(29,856)
Equity income (loss) from NEC TOKIN	0	0	0	0
Net income (loss)	(4,998)	7,194	(17,203)	(29,856)
Guarantor Subsidiaries
Revenues [Abstract]
Net sales	217,526	222,770	431,039	444,540
Operating costs and expenses:
Cost of sales	169,559	173,470	336,662	354,984
Selling, general and administrative expenses	18,717	16,511	36,206	39,990
Research and development	4,499	4,218	8,873	8,602
Restructuring charges	3,452	941	3,591	1,456
Write down of long-lived assets	6,193		6,193
Net (gain) loss on sales and disposals of assets	634	(400)	1,023	(753)
Total operating costs and expenses	203,054	194,740	392,548	404,279
Operating income (loss)	14,472	28,030	38,491	40,261
Interest income	0	0	3	0
Interest expense	379	265	778	598
Change in value of NEC TOKIN option	(1,600)	(2,200)	10,400	27,000
Other (income) expense, net	(8,469)	(9,265)	(17,885)	(17,068)
Equity in earnings of subsidiaries	0	0	0	0
Income (loss) from continuing operations before income taxes and equity income (loss) from NEC TOKIN	7,224	20,700	9,425	(4,405)
Income tax expense (benefit)	19	123	57	(364)
Income (loss) from continuing operations before equity income (loss) from NEC TOKIN	7,205	20,577	9,368	(4,041)
Equity income (loss) from NEC TOKIN	181	162	404	1,747
Net income (loss)	7,386	20,739	9,772	(2,294)
Non-Guarantor Subsidiaries
Revenues [Abstract]
Net sales	169,343	175,473	339,893	357,073
Operating costs and expenses:
Cost of sales	157,295	167,722	318,525	333,952
Selling, general and administrative expenses	10,738	11,255	21,948	24,125
Research and development	2,526	1,868	5,019	3,877
Restructuring charges	546	(918)	1,095	391
Write down of long-lived assets	0		0
Net (gain) loss on sales and disposals of assets	(265)	103	(563)	398
Total operating costs and expenses	170,840	180,030	346,024	362,743
Operating income (loss)	(1,497)	(4,557)	(6,131)	(5,670)
Interest income	(6)	(3)	(12)	(6)
Interest expense	135	81	236	292
Change in value of NEC TOKIN option	0	0	0	0
Other (income) expense, net	531	2,890	2,991	690
Equity in earnings of subsidiaries	0	0	0	0
Income (loss) from continuing operations before income taxes and equity income (loss) from NEC TOKIN	(1,095)	(1,745)	(3,364)	(5,266)
Income tax expense (benefit)	811	1,315	2,573	1,554
Income (loss) from continuing operations before equity income (loss) from NEC TOKIN	(1,906)	(3,060)	(5,937)	(6,820)
Equity income (loss) from NEC TOKIN	0	0	0	0
Net income (loss)	$ (1,906)	$ (3,060)	$ (5,937)	$ (6,820)