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Minimum Regulatory Capital Requirement (Tables) | 12 Months Ended
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Dec. 31, 2012
Minimum Regulatory Capital Requirement [Abstract] |
Company's and the bank's actual capital amounts and ratios | As of December 31, 2011, the most recent notifications from the Office of the Comptroller of the Currency categorized the bank as well capitalized under the regulatory framework for prompt corrective action. To be categorized as well capitalized, an institution must maintain minimum total risk-based, Tier 1 risk-based and Tier 1 leverage ratios, as set forth in the following tables. There are no conditions or events since these notifications that management believes have changed the bank's category. The Company's and the bank's actual capital amounts and ratios as of December 31, 2012 and 2011 are also presented in the following tables.
|  | Actual |  | Minimum Capital Requirement |  | Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions |
|  | Amount |  | Ratio |  | Amount | Ratio |  | Amount | Ratio |
December 31, 2012 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total capital (to risk weighted assets) |  |  |  |  |  |  |  |  |  |  |  |  |  |
NBI consolidated |  | $ | 151,824 |  | 22.4 | % | $ | 54,225 | 8.00 | % |  | N/A | N/A |
NBB |  |  | 148,684 |  | 22.0 | % |  | 53,984 | 8.00 | % | $ | 67,481 | 10.00 | %
Tier 1 capital (to risk weighted assets) |  |  |  |  |  |  |  |  |  |  |  |  |  |
NBI consolidated |  | $ | 143,472 |  | 21.2 | % | $ | 27,113 | 4.00 | % |  | N/A | N/A |
NBB |  |  | 140,335 |  | 20.8 | % |  | 26,992 | 4.00 | % | $ | 40,488 | 6.00 | %
Tier 1 capital (to average assets) |  |  |  |  |  |  |  |  |  |  |  |  |  |
NBI consolidated |  | $ | 143,472 |  | 13.3 | % | $ | 43,010 | 4.00 | % |  | N/A | N/A |
NBB |  |  | 140,335 |  | 13.1 | % |  | 42,973 | 4.00 | % | $ | 53,716 | 5.00 | %
|  | Actual |  | Minimum Capital Requirement |  | Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions |
|  | Amount |  | Ratio |  | Amount | Ratio |  | Amount | Ratio |
December 31, 2011 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total capital (to risk weighted assets) |  |  |  |  |  |  |  |  |  |  |  |  |  |
NBI consolidated |  | $ | 140,228 |  | 20.9 | % | $ | 53,615 | 8.0 | % |  | N/A | N/A |
NBB |  |  | 136,932 |  | 20.5 | % |  | 53,348 | 8.0 | % | $ | 66,684 | 10.0 | %
Tier 1 capital (to risk weighted assets) |  |  |  |  |  |  |  |  |  |  |  |  |  |
NBI consolidated |  | $ | 132,160 |  | 19.7 | % | $ | 26,807 | 4.0 | % |  | N/A | N/A |
NBB |  |  | 128,864 |  | 19.3 | % |  | 26,674 | 4.0 | % | $ | 40,011 | 6.0 | %
Tier 1 capital (to average assets) |  |  |  |  |  |  |  |  |  |  |  |  |  |
NBI consolidated |  | $ | 132,160 |  | 12.7 | % | $ | 41,598 | 4.0 | % |  | N/A | N/A |
NBB |  |  | 128,864 |  | 12.5 | % |  | 41,293 | 4.0 | % | $ | 51,617 | 5.0 | %

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- Definition Tabular disclosure of the capital amounts and ratios as of the balance sheet date, indicating whether the entity or entities are in compliance with regulatory capital requirements, by entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1G -URI http://asc.fasb.org/extlink&oid=7881181&loc=SL5958577-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-DEP -Paragraph 18 -IssueDate 2006-05-01 -Chapter 17 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=7881181&loc=d3e65071-112826 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=7881181&loc=SL5958568-112826 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=7881181&loc=SL5958570-112826 + Details
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