Investment in NEC TOKIN - Narrative (Details) (USD $)	12 Months Ended			0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Feb. 01, 2013	Mar. 12, 2012
Schedule of Equity Method Investments [Line Items]
Document Period End Date	Mar. 31, 2015
Value of net call derivative options	$ 1,003,000	$ 0
Gain (loss) on options	2,100,000	3,111,000	0
Investment in NEC TOKIN (excludes non cash investment)	0	0	50,917,000
Loss Contingency, Number of Co-Defendants	20
Loss Contingency, Estimate of Possible Loss	30,000,000
KEC
Schedule of Equity Method Investments [Line Items]
Business Combination, Indemnification Assets, Range of Outcomes, Value, Low	8,500,000
Stockholders Agreement | KEC
Schedule of Equity Method Investments [Line Items]
Receivables balance under agreement	600,000	700,000
NEC TOKIN
Schedule of Equity Method Investments [Line Items]
KEMET's equity ownership %	34.00%	34.00%	34.00%
Revenue from Related Parties	13,500,000	6,000,000
Related Party Transaction, Purchases from Related Party	3,600,000	1,800,000
Accounts receivable	3,300,000	2,000,000
Accounts payable	800,000	100,000
NEC TOKIN | KEC
Schedule of Equity Method Investments [Line Items]
Purchase price				54,500,000
Transaction expenses				4,500,000
NEC TOKIN | Stock Purchase Agreement | KEC
Schedule of Equity Method Investments [Line Items]
Common stock acquired					51.00%
KEMET's equity ownership %					34.00%
Purchase price paid				50,000,000
Investment in NEC TOKIN (excludes non cash investment)				50,000,000
NEC TOKIN | Stockholders Agreement
Schedule of Equity Method Investments [Line Items]
Number of director positions	7
NEC TOKIN | Stockholders Agreement | KEC
Schedule of Equity Method Investments [Line Items]
Number of director positions	4
NEC TOKIN | Option Agreement | KEC
Schedule of Equity Method Investments [Line Items]
KEMET's equity ownership %	49.00%
Purchase price for expected additional shares that may be acquired	50,000,000
Ownership interest maintained after acquisition of additional shares (as a percent)	51.00%
LTM EBITDA multiple	6
NEC TOKIN | Put Option
Schedule of Equity Method Investments [Line Items]
Gain (loss) on options		3,100,000
NEC TOKIN | Put Option | KEC
Schedule of Equity Method Investments [Line Items]
LTM EBITDA multiple	6
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | NEC TOKIN | Put Option
Schedule of Equity Method Investments [Line Items]
Gain (loss) on options	2,100,000
NEC TOKIN options, net	5,700,000	3,600,000
Equity Method Investments [Member] | Stockholders Agreement
Schedule of Equity Method Investments [Line Items]
Business Combination, Indemnification Assets, Range of Outcomes, Value, Low	$ 25,000,000