Annual report pursuant to Section 13 and 15(d)

Debt - Revolving Line of Credit, Narrative (Details)

v3.19.1
Debt - Revolving Line of Credit, Narrative (Details) - USD ($)
12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
May 02, 2016
Dec. 19, 2014
Sep. 30, 2010
May 05, 2010
Revolving line of credit            
Debt Instrument [Line Items]            
Credit facility, remaining borrowing capacity $ 66,000,000          
Revolving Line of Credit            
Debt Instrument [Line Items]            
Maximum borrowing capacity       $ 75,000,000 $ 50,000,000.0  
Current borrowing capacity     $ 75,000,000 60,000,000    
Credit facility, remaining borrowing capacity       15,000,000    
Number of days considered 5 days          
Availability under credit facility (as a percent) 10.00%          
Availability under credit facility $ 7,500,000          
Fixed charge coverage ratio 1.0          
Consecutive period of non occurrence of any condition to maintain fixed charge coverage ratio 45 days          
Required aggregate revolver commitments to maintain fixed charge coverage ratio (as a percent) 10.00%          
Required aggregate revolver commitments to maintain fixed charge coverage ratio $ 7,500,000          
Debt issuance cost, net of amortization $ 100,000 $ 100,000        
Revolving Line of Credit | LIBOR            
Debt Instrument [Line Items]            
Debt Instrument, Basis Spread on Variable Rate 1.00%          
Revolving Line of Credit | Greater than 33.3% and less than 66.6%            
Debt Instrument [Line Items]            
Unused line fee (as a percent) 0.50%          
Revolving Line of Credit | Greater than 33.3% and less than 66.6% | Maximum            
Debt Instrument [Line Items]            
Average daily balance as percentage of total revolving commitment 50.00%          
Revolving Line of Credit | Greater than or equal to 66.6%            
Debt Instrument [Line Items]            
Unused line fee (as a percent) 0.375%          
Revolving Line of Credit | Greater than or equal to 66.6% | Maximum            
Debt Instrument [Line Items]            
Average daily balance as percentage of total revolving commitment 50.00%          
Revolving Line of Credit | KEMET Singapore            
Debt Instrument [Line Items]            
Percentage of assets pledged as collateral 100.00%          
Foreign Line of Credit            
Debt Instrument [Line Items]            
Maximum borrowing capacity       $ 30,000,000.0    
Foreign Line of Credit | LIBOR | Minimum            
Debt Instrument [Line Items]            
Debt Instrument, Basis Spread on Variable Rate 2.25%          
Foreign Line of Credit | LIBOR | Maximum            
Debt Instrument [Line Items]            
Debt Instrument, Basis Spread on Variable Rate 2.75%          
Foreign Line of Credit | Base Rate | Minimum            
Debt Instrument [Line Items]            
Debt Instrument, Basis Spread on Variable Rate 1.25%          
Foreign Line of Credit | Base Rate | Maximum            
Debt Instrument [Line Items]            
Debt Instrument, Basis Spread on Variable Rate 1.75%          
Foreign Line of Credit | KEMET Singapore            
Debt Instrument [Line Items]            
Borrowing base component one, percentage of borrower's accounts receivable that satisfy certain eligibility criteria       85.00%    
Domestic Line of Credit            
Debt Instrument [Line Items]            
Number of days considered 5 days          
Availability under credit facility $ 3,750,000          
Required aggregate revolver commitments to maintain fixed charge coverage ratio $ 3,750,000          
Domestic Line of Credit | LIBOR | Minimum            
Debt Instrument [Line Items]            
Debt Instrument, Basis Spread on Variable Rate 2.00%          
Domestic Line of Credit | LIBOR | Maximum            
Debt Instrument [Line Items]            
Debt Instrument, Basis Spread on Variable Rate 2.50%          
Domestic Line of Credit | Base Rate | Minimum            
Debt Instrument [Line Items]            
Debt Instrument, Basis Spread on Variable Rate 1.00%          
Domestic Line of Credit | Base Rate | Maximum            
Debt Instrument [Line Items]            
Debt Instrument, Basis Spread on Variable Rate 1.50%          
Domestic Line of Credit | KEMET Electronics Corporation            
Debt Instrument [Line Items]            
Borrowing base component one, percentage of borrower's accounts receivable that satisfy certain eligibility criteria       85.00%    
Borrowing base component two, fixed amount for determining second component for borrowing base       $ 6,000,000    
Borrowing base component two, percentage of net book value of inventory of borrower that satisfies certain eligibility criteria       40.00%    
Borrowing base component three, percentage of net orderly liquidation percentage of the appraised value of inventory that satisfies certain eligibility criteria       85.00%    
Borrowing base component three, fixed amount for determining second component for borrowing base       $ 5,100,000    
Borrowing base component three, percentage of net orderly liquidation percentage of the appraised value of equipment that satisfies certain eligibility criteria       80.00%    
10.5% Senior Notes            
Debt Instrument [Line Items]            
Stated interest rate (as a percent)           10.50%