Common stock (Incentive stock option plans) (Details)	6 Months Ended
Jun. 30, 2012
Class of Stock [Line Items]
Number of equity incentive plans	3
Stock options \| 2012 Plan
Class of Stock [Line Items]
Vesting period (in years)	4 years
Award vesting percentage at end of one year (percent)	25.00%
Expiration period of granted options (in years)	10 years

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

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Percentage

+ References

No definition available.

+ Details

Name:	vcra_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPercentage
Namespace Prefix:	vcra_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangement By Share-based Payment Award, Expiration Period of Granted Options

+ References

No definition available.

+ Details

Name:	vcra_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpirationPeriodOfGrantedOptions
Namespace Prefix:	vcra_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangements by Share-based Payment Award, Number Of Equity Incentive Plans

+ References

No definition available.

+ Details

Name:	vcra_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNumberOfEquityIncentivePlans
Namespace Prefix:	vcra_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant