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Junior Subordinated Debt - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2015 | Dec. 31, 2014
First National (VA) Statutory Trust III [Member] |  |
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items] |  |
Formation of wholly-owned subsidiary | Jul. 24, 2006 |
Preferred securities issued through pooled underwriting date | Jul. 31, 2006 |
Issuance of trust preferred securities | $ 4.0 |
LIBOR-indexed floating rate of interest | 1.93% | 1.84%
Junior subordinated debt | $ 4.1 |
Securities mandatory redemption date | Oct. 01, 2036 |
Maximum capital required for capital adequacy | 25.00% |
First National (VA) Statutory Trust II [Member] |  |
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items] |  |
Formation of wholly-owned subsidiary | Jun. 08, 2004 |
Preferred securities issued through pooled underwriting date | Jun. 17, 2004 |
Issuance of trust preferred securities | $ 5.0 |
LIBOR-indexed floating rate of interest | 3.13% | 2.84%
Junior subordinated debt | $ 5.2 |
Securities mandatory redemption date | Jun. 17, 2034 |

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- Definition Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399 + Details
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- Definition Date the debt instrument was issued, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Including the current and noncurrent portions, the carrying value of junior subordinated long-term debt owed to unconsolidated subsidiary trusts as of the balance sheet date. Such debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets and was initially scheduled to be repaid after one year or beyond the normal operating cycle if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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