Deposits (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deposits, by Component, Alternative [Abstract]
Noninterest-bearing demand deposits	$ 251,235	$ 234,673
Interest-bearing demand deposits	362,406	349,802
Savings deposits	74,436	68,236
Money market deposits	455,734	431,790
Brokered deposits	55,590	112,066
Time deposits less than $100,000	417,421	538,306
Time deposits $100,000 or more	290,166	394,238
Total deposits	$ 1,906,988	$ 2,129,111
Noninterest-bearing demand deposits, Percentage	13.17%	11.02%
Interest-bearing demand deposits, Percentage	19.00%	16.43%
Savings deposits, Percentage	3.90%	3.20%
Money market deposits, Percentage	23.90%	20.28%
Brokered deposits, Percentage	2.92%	5.27%
Time deposits less than $100,000, Percentage	21.89%	25.28%
Time deposits $100,000 or more, Percentage	15.22%	18.52%
Total deposits, Percentage	100.00%	100.00%

Percentage of Deposits

No definition available.

Name:	fnbn_PercentageOfDeposits
Namespace Prefix:	fnbn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Noninterest-bearing Domestic Deposits to Deposits, Demand

+ References

No definition available.

+ Details

Name:	fnbn_PercentageOfNoninterestBearingDomesticDepositsToDepositsDemand
Namespace Prefix:	fnbn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Time Deposits, Less than 100000 to Deposits

+ References

No definition available.

+ Details

Name:	fnbn_PercentageOfTimeDepositsLessThan100000ToDeposits
Namespace Prefix:	fnbn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Time Deposits, More than 100000 to Deposits

+ References

No definition available.

+ Details

Name:	fnbn_PercentageOfTimeDepositsMoreThan100000ToDeposits
Namespace Prefix:	fnbn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.12)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Paragraph 37, 38, 39

-IssueDate 2006-05-01

-Chapter 13

-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.

+ Details

Name:	us-gaap_Deposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DepositsByComponentAlternativeAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of interest-bearing domestic third-party deposits placed by or through the assistance of a deposit broker, also known as brokered deposit liabilities.

+ References

+ Details

Name:	us-gaap_InterestBearingDomesticDepositBrokered
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of money in interest-bearing domestic accounts that entitle the depositor to withdraw funds at any time without prior notice, also known as demand deposits.

+ References

+ Details

Name:	us-gaap_InterestBearingDomesticDepositDemand
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of interest-bearing domestic money market demand account deposit liabilities.

+ References

+ Details

Name:	us-gaap_InterestBearingDomesticDepositMoneyMarket
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of interest-bearing domestic savings deposit liabilities. Saving deposits bear interest and have no stated maturity.

+ References

+ Details

Name:	us-gaap_InterestBearingDomesticDepositSavings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of money in noninterest-bearing domestic accounts that entitle the depositor to withdraw funds at any time without prior notice, also known as demand deposits.

+ References

+ Details

Name:	us-gaap_NoninterestBearingDomesticDepositDemand
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage of interest-bearing domestic brokered deposit liabilities to total deposit liabilities.

+ References

No definition available.

+ Details

Name:	us-gaap_PercentageOfInterestBearingDomesticDepositsToDepositsBrokered
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of interest-bearing domestic demand deposit liabilities to total deposit liabilities.

+ References

No definition available.

+ Details

Name:	us-gaap_PercentageOfInterestBearingDomesticDepositsToDepositsDemand
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of interest-bearing domestic money market demand account deposit liabilities to total deposit liabilities.

+ References

No definition available.

+ Details

Name:	us-gaap_PercentageOfInterestBearingDomesticDepositsToDepositsMoneyMarket
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of interest-bearing domestic savings deposit liabilities to total deposit liabilities.

+ References

No definition available.

+ Details

Name:	us-gaap_PercentageOfInterestBearingDomesticDepositsToDepositsSavings
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate amount of domestic time deposits (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $100,000 or more.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 405

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6479006&loc=d3e64164-112818

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 14

-Subparagraph e

-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.

+ Details

Name:	us-gaap_TimeDeposits100000OrMoreDomestic
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The aggregate amount of domestic or foreign time deposits (including certificates of deposits, individual retirement accounts and open accounts) that total to less than $100,000.

+ References

No definition available.

+ Details

Name:	us-gaap_TimeDepositsLessThan100000
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant