Note 8 - Stock-based Compensation Expense (Details Textual) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Payment Arrangement, Expense, Par Value	$ 99,000	$ 280,000	$ 476,000	$ 704,000

Represents the amount of share-based payment arrangement, expense, par Value.

No definition available.

Name:	cvv_SharebasedPaymentArrangementExpenseParValue
Namespace Prefix:	cvv_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration