Inventories - Noncurrent - General Information (Details)	6 Months Ended
Sep. 30, 2019
Inventories
Weighted average age of noncurrent inventories	1 year 1 month 6 days

Represents the weighted average age of the non-current inventories on hand as of the balance sheet date.

No definition available.

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