Note 8 - Stock-based Compensation Expense (Details Textual) - USD ($)	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Share-based Payment Arrangement, Expense, Par Value	$ 73,000	$ 199,000

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