Basis of Financial Statement Presentation - Revenue Recognition Narrative (Details)	6 Months Ended
Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Period of product warranty	1 year

Represents the period of warranty that the entity's goods and services meet certain specifications. The entity provides these warranties to its customers.

No definition available.

Name:	kem_ProductWarrantyPeriod
Namespace Prefix:	kem_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration