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Note 12 - Minimum Regulatory Capital Requirement (Details) - Minimum Capital Requirements (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
NBI Consolidated [Member]
Total capital (to risk weighted assets)
Total capital (to risk weighted assets) actual amount (in Dollars)	$ 162,763	$ 151,824
Total capital (to risk weighted assets) actual ratio	23.60%	22.40%
Total capital (to risk weighted assets) minimum capital requirement amount (in Dollars)	55,192	54,225
Total capital (to risk weighted assets) minimum capital requirement ratio	8.00%	8.00%
Tier 1 capital (to risk weighted assets)
Tier 1 capital (to risk weighted assets) actual amount (in Dollars)	154,536	143,472
Tier 1 capital (to risk weighted assets) actual ratio	22.40%	21.20%
Tier 1 capital (to risk weighted assets) minimum capital requirement amount (in Dollars)	27,596	27,113
Tier 1 capital (to risk weighted assets) minimum capital requirement ratio	4.00%	4.00%
Tier 1 capital (to average assets)
Tier 1 capital (to average assets) actual amount (in Dollars)	154,536	143,472
Tier 1 capital (to average assets) actual ratio	14.10%	13.30%
Tier 1 capital (to average assets) minimum capital requirement amount (in Dollars)	43,946	43,010
Tier 1 capital (to average assets) minimum capital requirement ratio	4.00%	4.00%
NBB [Member]
Total capital (to risk weighted assets)
Total capital (to risk weighted assets) actual amount (in Dollars)	160,049	148,684
Total capital (to risk weighted assets) actual ratio	23.30%	22.00%
Total capital (to risk weighted assets) minimum capital requirement amount (in Dollars)	54,980	53,984
Total capital (to risk weighted assets) minimum capital requirement ratio	8.00%	8.00%
Total capital (to risk weighted assets) minimum to be well capitalized under prompt corrective action provisions amount (in Dollars)	68,726	67,481
Total capital (to risk weighted assets) minimum to be well capitalized under prompt corrective action provisions ratio	10.00%	10.00%
Tier 1 capital (to risk weighted assets)
Tier 1 capital (to risk weighted assets) actual amount (in Dollars)	151,822	140,335
Tier 1 capital (to risk weighted assets) actual ratio	22.10%	20.80%
Tier 1 capital (to risk weighted assets) minimum capital requirement amount (in Dollars)	27,490	26,992
Tier 1 capital (to risk weighted assets) minimum capital requirement ratio	4.00%	4.00%
Tier 1 capital (to risk weighted assets) minimum to be well capitalized under prompt corrective action provisions amount (in Dollars)	41,235	40,488
Tier 1 capital (to risk weighted assets) minimum to be well capitalized under prompt corrective action provisions ratio	6.00%	6.00%
Tier 1 capital (to average assets)
Tier 1 capital (to average assets) actual amount (in Dollars)	151,822	140,335
Tier 1 capital (to average assets) actual ratio	13.80%	13.10%
Tier 1 capital (to average assets) minimum capital requirement amount (in Dollars)	43,904	42,973
Tier 1 capital (to average assets) minimum capital requirement ratio	4.00%	4.00%
Tier 1 capital (to average assets) minimum to be well capitalized under prompt corrective action provisions amount (in Dollars)	$ 54,880	$ 53,716
Tier 1 capital (to average assets) minimum to be well capitalized under prompt corrective action provisions ratio	5.00%	5.00%

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The amount of total capital as defined in the regulations.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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Tier 1 Risk Based Capital as defined in the regulations.

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