XML 58 R46.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Fair Value Measurements Text Tag (Details) | 6 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2016 | Mar. 31, 2016
Fair Value Disclosures [Abstract] |  |
Percent of Total Assets Level 3 | 0.08% | 0.05%

X
- Definition Percent of Total Assets Level 3 + References No definition available. + Details
Name: | carv_PercentOfTotalAssetsLevel3
Namespace Prefix: | carv_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_FairValueDisclosuresAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration