Note 6 - Investment in Macrophage Therapeutics, Inc. (Details Textual)	1 Months Ended
Mar. 31, 2015 shares
Macrophage Therapeutics [Member]
Convertible Preferred Stock Shares Issued Upon Conversion, Per Unit (in shares)	1

Represents the number of convertible preferred stock shares issued upon conversion per unit.

No definition available.

Name:	navb_ConvertiblePreferredStockSharesIssuedUponConversionPerUnit
Namespace Prefix:	navb_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration