Annual report pursuant to Section 13 and 15(d)

Equity (Details)

Equity (Details) (USD $)	1 Months Ended			12 Months Ended			1 Months Ended		0 Months Ended	1 Months Ended
Equity (Details) (USD $)	Sep. 30, 2013	Apr. 30, 2013	Feb. 28, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2013	Nov. 30, 2014	Sep. 24, 2016	Mar. 31, 2013	Mar. 31, 2014	Mar. 13, 2015
Class of Stock [Line Items]
Issued stock in connection with public offerings, net of costs, shares	10,563,381	2,100,000	1,542,389
Shares issued price per share	$ 2.84us-gaap_SharesIssuedPricePerShare	$ 2.43us-gaap_SharesIssuedPricePerShare	$ 3.10us-gaap_SharesIssuedPricePerShare
Proceeds from issuance of common stock net of issuance costs	$ 28,800,000	$ 4,800,000	$ 4,500,000
Proceeds from issuance of common stock	30,000,000			87,984	41,303,750	2,724,189
Warrants, exercise price				$ 2.27
Placement agent fees	999,000navb_PlacementAgentFees
Placement agent fees as a percentage of gross proceeds	3.30%
Warrants outstanding				1,764,781
Warrants, weighted average exercise price				$ 2.27
Repayments of notes payable				25,000,000us-gaap_RepaymentsOfNotesPayable	5,982,155us-gaap_RepaymentsOfNotesPayable	1,285,046us-gaap_RepaymentsOfNotesPayable
Common stock reserved for future issuance				21,887,675
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Conversion of Series B preferred stock to common stock, shares					2,364.9		2,364.9
Common Stock [Member]
Class of Stock [Line Items]
Issued stock upon exercise of warrants, net, shares								3,843,223
Number of common shares underlying Series B Preferred Stock				14,777,130
Shares conversion, number of common stock equivalent to each preferred stock				3,270			3,270
Minimum [Member]
Class of Stock [Line Items]
Warrants, exercise price				$ 1.918
Maximum [Member]
Class of Stock [Line Items]
Warrants, exercise price				$ 3.04
Platinum Montaur Life Sciences Llc Credit Facility [Member]
Class of Stock [Line Items]
Repayments of notes payable					4,800,000		4,781,333
Subsequent Event [Member]
Class of Stock [Line Items]
Shares issued price per share												$ 3.00
Warrants, expiration date									Sep. 24, 2016
Series JJ Warrants [Member]
Class of Stock [Line Items]
Warrants, number of securities called by warrants	3,169,015
Warrants, exercise price	$ 3.83
Reclassification to additional paid in capital								7,700,000
Series W Warrants [Member]
Class of Stock [Line Items]
Warrants exercised						6,000,000
Issued stock upon exercise of warrants, net, shares						6,000,000
Proceeds from warrant exercises						1,920,000
Series X Warrants [Member] \| Platinum Montaur Life Sciences Llc Credit Facility [Member]
Class of Stock [Line Items]
Warrants exercised										3,000,000
Issued stock upon exercise of warrants, net, shares										3,000,000
Proceeds from warrant exercises										$ 1,380,000
Series X Warrants And Series AA Warrants [Member] \| Platinum Montaur Life Sciences Llc Credit Facility [Member]
Class of Stock [Line Items]
Number of common shares underlying Series B Preferred Stock				7,733,223			7,733,223
Series HH Warrants [Member]
Class of Stock [Line Items]
Warrants, number of securities called by warrants							301,205
Warrants, exercise price				$ 2.49
Warrants, expiration date				Jun. 25, 2023
Warrants outstanding				301,205
Series HH Warrants [Member] \| General Electric Capital Corporation [Member]
Class of Stock [Line Items]
Warrants, exercise price							2.49
Series II Warrants [Member]
Class of Stock [Line Items]
Warrants, number of securities called by warrants							275,000
Warrants, exercise price				$ 3.04
Warrants, expiration date				Jun. 25, 2018
Warrants outstanding				275,000
Class of warrant term							5 years
Series II Warrants [Member] \| Maximum [Member]
Class of Stock [Line Items]
Warrants, exercise price							3.04
Series KK Warrants [Member]
Class of Stock [Line Items]
Warrants, exercise price				$ 1.918
Warrants, expiration date				Mar. 04, 2021
Warrants outstanding				391,032
Series KK Warrants [Member] \| Oxford Finance, LLC [Member]
Class of Stock [Line Items]
Warrants, exercise price											$ 1.918
Issued stock upon exercise of warrants, net, shares											391,032