Business and Organization (Details)	6 Months Ended
Sep. 30, 2019
Business and Organization
Long-term service contracts, maximum term	20 years

Represents the maximum term of long term service contracts.

No definition available.

Name:	cpst_LongTermServiceContractsMaximumTerm
Namespace Prefix:	cpst_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration