| **Capital Matters**            | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       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| **Capital Matters [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           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| Capital Matters                | Capital MattersFNB and each of its bank subsidiaries are required to comply with capital adequacy requirements established by the federal banking agencies. Failure to meet these minimum capital requirements can initiate certain mandatory – and possible additional discretionary – actions by regulators that, if undertaken, could have a direct material effect on FNB’s and each bank’s financial statements. Under the capital adequacy guidelines, FNB and each bank must meet specific capital guidelines that involve quantitative measures of assets, liabilities, and certain off-balance-sheet items as calculated under regulatory accounting practices. FNB and each bank’s capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weighting, and other factors. In addition, the prompt corrective action provisions of federal law require the federal banking agencies to take action to resolve problems of insured depository institutions such as CommunityOne and Granite as their capital levels decrease.Quantitative measures established by regulation to ensure capital adequacy require each bank to maintain minimum amounts and ratios (set forth in the accompanying table) of total and Tier 1 capital (as defined in the regulations) to risk-weighted assets (as defined), and of Tier 1 capital to average assets (as defined).       Minimum Regulatory Requirement to be Well Capitalized(dollars in thousands) Actual For CapitalAdequacy Purposes Under PromptCorrective ActionProvisions Pursuantto Order  Amount Ratio Amount Ratio Amount Ratio RatioDecember 31, 2012                  Total Capital (to Risk Weighted Assets)                  Consolidated $158,993 12.34% $103,051   8.00% N/A      CommunityOne Bank, N.A. 103,976 11.40 72,997   8.00 $91,247   10.00% 12.00%Bank of Granite 60,896 16.30 29,893   8.00 37,366   10.00 12.00Tier 1 Capital (to Risk Weighted Assets)                  Consolidated 119,242 9.26 $51,525   — N/A      CommunityOne Bank, N.A. 92,418 10.13 36,499   4.00 $54,748   6.00% 9.00%Bank of Granite 56,209 15.04 14,946   4.00 22,420   6.00 8.00Tier 1 Capital (to Average Assets)                  Consolidated 119,242 5.45 $87,567   — N/A      CommunityOne Bank, N.A. 92,418 6.17 59,909   4.00 $74,886   5.00% 9.00%Bank of Granite 56,209 8.12 27,675   4.00 34,594   5.00 8.00                   December 31, 2011                  Total Capital (to Risk Weighted Assets)                  Consolidated $193,725 13.81% $112,245   N/A N/A      CommunityOne Bank, N.A. 136,761 14.52 75,363   8.00 $94,204   10.00% 12.00%Bank of Granite 54,647 12.04 36,305   8.00 45,382   10.00 12.00Tier 1 Capital (to Risk Weighted Assets)                  Consolidated 164,253 11.71 56,123   N/A N/A      CommunityOne Bank, N.A. 124,639 13.23 37,682   4.00 $56,522   6.00% 9.00%Bank of Granite 54,633 12.04 18,153   4.00 27,229   6.00 8.00Tier 1 Capital (to Average Assets)                  Consolidated 164,253 6.70 98,092   N/A N/A      CommunityOne Bank, N.A. 124,639 7.39 67,426   4.00 $84,282   5.00% 9.00%Bank of Granite 54,633 7.19 30,410   4.00 38,013   5.00 8.00CommunityOne is designated as “adequately capitalized” by the OCC because it is subject to an order or written agreement that requires the institution to meet and maintain a specific capital level.  CommunityOne currently is not in compliance with the capital requirements of the CommunityOne Order.  Granite is under a regulatory obligation to maintain capital in excess of regulatory minimums and is in compliance with that obligation.Certain regulatory requirements restrict the lending of funds by CommunityOne and Granite to FNB and the amount of dividends which can be paid to FNB. Since 2009, these regulatory requirements have prohibited CommunityOne from declaring dividends payable to FNB without the approval of the OCC. Similar requirements would prohibit Granite from declaring dividends payable to FNB without the approval of the FDIC and the NCCOB. The CommunityOne Order described in Note 2 “Regulatory Matters” further prohibit CommunityOne from paying dividends or making distributions to FNB. Each of CommunityOne and Granite are no longer required to maintain average reserve balances with the FRBR based on a percentage of deposits as of December 31, 2012. |

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| - Definition
The entire disclosure for banks, savings institutions, and credit unions, for regulatory capital requirements imposed by the Federal Reserve System (FRB), the Federal Deposit Insurance Corporation (FDIC), the Office of Thrift Supervision (OTS) or for any state imposed capital requirements, as applicable.  The disclosure may include (1) a description of regulatory capital requirements (a) for capital adequacy purposes and (b) established by the prompt corrective action provisions of Section 38 of the Federal Depository Insurance Act; (2) the actual or possible material effects of noncompliance with such requirements; (3) whether the entity is in compliance with the regulatory capital requirements including (a) required and actual ratios and amounts of Tier 1 leverage, Tier 1 risk-based, and total risk-based capital, tangible capital (for savings institutions), and Tier 3 capital for market risk (for certain banks and bank holding companies), (b) factors that may significantly affect capital adequacy; (4) the prompt corrective action category in which the entity was classified as of its most recent notification; (5) whether management believes any conditions or events since notification have changed the entity's category. Also may include additional information that might be disclosed in situations where substantial doubt about the entity's ability to continue as a going concern for a reasonable period of time.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1C -URI http://asc.fasb.org/extlink&oid=7881181&loc=SL5958572-112826Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1D -URI http://asc.fasb.org/extlink&oid=7881181&loc=SL5958573-112826Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-DEP -Paragraph 15, 16, 17 -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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1E -URI http://asc.fasb.org/extlink&oid=7881181&loc=SL5958574-112826Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=7881181&loc=SL5958568-112826Reference 6: 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=SL5958570-112826Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -URI http://asc.fasb.org/extlink&oid=7881181&loc=d3e65071-112826Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=7881181&loc=SL5958569-112826Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1F -URI http://asc.fasb.org/extlink&oid=7881181&loc=SL5958575-112826Reference 10: 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
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