Note 12 - Minimum Regulatory Capital Requirement (Tables)

12 Months Ended

Dec. 31, 2015

Disclosure Text Block [Abstract]

Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block]

	Actual					Minimum Capital Requirement					Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions
	Amount		Ratio			Amount		Ratio			Amount		Ratio
December 31, 2015
Total capital (to risk weighted assets)
NBI consolidated	$	184,054		25.5	%	$	57,681		8.0	%		N/A		N/A
NBB		181,926		25.3	%		57,526		8.0	%	$	71,908		10.0	%
Tier 1 capital (to risk weighted assets)
NBI consolidated	$	175,757		24.4	%	$	43,261		6.0	%		N/A		N/A
NBB		173,629		24.1	%		43,145		6.0	%	$	57,526		8.0	%
Common Equity Tier 1 capital (to risk weighted assets)
NBI consolidated	$	175,757		24.4	%	$	32,446		4.5	%		N/A		N/A
NBB		173,629		24.1	%		32,358		4.5	%	$	46,740		6.5	%
Tier 1 capital (to average assets)
NBI consolidated	$	175,757		15.1	%	$	46,594		4.0	%		N/A		N/A
NBB		173,629		14.9	%		46,648		4.0	%	$	58,310		5.0	%

	Actual					Minimum Capital Requirement					Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions
	Amount		Ratio			Amount		Ratio			Amount		Ratio
December 31, 2014
Total capital (to risk weighted assets)
NBI consolidated	$	172,976		24.9	%	$	55,615		8.0	%		N/A		N/A
NBB		170,665		24.6	%		55,438		8.0	%	$	69,298		10.0	%
Tier 1 capital (to risk weighted assets)
NBI consolidated	$	164,713		23.7	%	$	27,807		4.0	%		N/A		N/A
NBB		162,402		23.4	%		27,719		4.0	%	$	41,579		6.0	%
Tier 1 capital (to average assets)
NBI consolidated	$	164,713		14.6	%	$	45,122		4.0	%		N/A		N/A
NBB		162,402		14.4	%		45,074		4.0	%	$	56,342		5.0	%