Summary of Significant Accounting Policies (Details 3)	6 Months Ended
Jun. 30, 2014 item
Goodwill and other intangible assets and impairment
Number of reporting units at significant risk for impairment	0

Represents the number of reporting units at significant risk for impairment.

No definition available.

Name:	cvd_NumberOfReportingUnitsAtSignificantRiskForImpairment
Namespace Prefix:	cvd_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration