Inventories - Non-Current (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Mar. 31, 2016
Inventories
Non-current inventory, 13 to 24 Months	$ 1,912
Non-current inventory, 25 to 36 Months	389
Non-current inventory, 37 to 48 Months	16
Total	$ 2,317	$ 2,143

Represents the portion of non-current inventory that the entity expects to convert to cash, sell or exchange within 13-24 months after the balance sheet date.

No definition available.

+ Details

Name:	cpst_InventoryNoncurrentPortionToBeConvertedWithinThirteenToTwentyFourMonths
Namespace Prefix:	cpst_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the portion of non-current inventory that the entity expects to convert to cash, sell or exchange within 37-48 months after the balance sheet date.

+ References

No definition available.

+ Details

Name:	cpst_InventoryNoncurrentPortionToBeConvertedWithinThirtySevenToFortyEightMonths
Namespace Prefix:	cpst_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the portion of non-current inventory that the entity expects to convert to cash, sell or exchange within 25-36 months after the balance sheet date.

+ References

No definition available.

+ Details

Name:	cpst_InventoryNoncurrentPortionToBeConvertedWithinTwentyFiveToThirtySixMonths
Namespace Prefix:	cpst_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_InventoryDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Inventories not expected to be converted to cash, sold or exchanged within the normal operating cycle.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(d))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_InventoryNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant