Note 3 - Securities

12 Months Ended

Dec. 31, 2015

Investments, Debt and Equity Securities [Abstract]

Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]

Note 3: Securities

The amortized cost and fair value of securities available for sale, with gross unrealized gains and losses, follows:

	December 31, 2015
Available for sale:	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Government agencies and corporations	$	216,897	$	519	$	4,952	$	212,464
States and political subdivisions		15,934		541		---		16,475
Mortgage-backed securities		1,199		120		---		1,319
Corporate debt securities		6,015		22		291		5,746
Other securities		189		---		62		127
Total securities available for sale	$	240,234	$	1,202	$	5,305	$	236,131

	December 31, 2014
Available for sale:	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Government agencies and corporations	$	197,740	$	973	$	4,494	$	194,219
States and political subdivisions		18,529		851		---		19,380
Mortgage-backed securities		1,830		184		---		2,014
Corporate debt securities		6,991		140		27		7,104
Other securities		189		---		62		127
Total securities available for sale	$	225,279	$	2,148	$	4,583	$	222,844

The amortized cost and fair value of single maturity securities available for sale at December 31, 2015, by contractual maturity, are shown below. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Mortgage-backed securities included in these totals are categorized by final maturity at December 31, 2015.

	December 31, 2015
Available for sale:	Amortized Cost		Fair Value
Due in one year or less	$	974	$	992
Due after one year through five years		68,172		68,177
Due after five years through ten years		32,062		31,836
Due after ten years		138,837		134,999
No maturity		189		127
	$	240,234	$	236,131

The Company holds restricted stock with the Federal Home Loan Bank and the Federal Reserve. Required ownership amounts are determined by the correspondent banks and the Company purchases stock from or sells stock back to the correspondents based on their calculations. The stock is held by member institutions only and is not actively traded. The Company held restricted stock of $1,129 as of December 31, 2015 and $1,089 as of December 31, 2014.

The amortized cost and fair value of securities held to maturity, with gross unrealized gains and losses, follows:

	December 31, 2015
Held to maturity:	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Government agencies and corporations	$	13,909	$	288	$	177	$	14,020
States and political subdivisions		136,373		6,179		330		142,222
Mortgage-backed securities		327		36		---		363
Corporate debt securities		1,419		10		2		1,427
Total securities held to maturity	$	152,028	$	6,513	$	509	$	158,032

	December 31, 2014
Held to maturity:	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Government agencies and corporations	$	18,922	$	350	$	245	$	19,027
States and political subdivisions		140,702		6,823		727		146,798
Mortgage-backed securities		415		51		---		466
Corporate debt securities		1,413		1		2		1,412
Total securities held to maturity	$	161,452	$	7,225	$	974	$	167,703

The amortized cost and fair value of single maturity securities held to maturity at December 31, 2015, by contractual maturity, are shown below. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Mortgage-backed securities included in these totals are categorized by final maturity at December 31, 2015.

	December 31, 2015
Held to maturity:	Amortized Cost		Fair Value
Due in one year or less	$	1,160	$	1,168
Due after one year through five years		13,011		13,849
Due after five years through ten years		21,288		22,317
Due after ten years		116,569		120,698
	$	152,028	$	158,032

Information pertaining to securities with gross unrealized losses at December 31, 2015 and 2014 aggregated by investment category and length of time that individual securities have been in a continuous loss position, follows:

	December 31, 2015
	Less Than 12 Months				12 Months or More
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
U. S. Government agencies and corporations	$	88,255	$	1,800	$	84,959	$	3,329
State and political subdivisions		3,449		24		10,161		306
Corporate debt securities		4,974		292		200		1
Other securities		---		---		127		62
Total temporarily impaired securities	$	96,678	$	2,116	$	95,447	$	3,698

	December 31, 2014
	Less Than 12 Months				12 Months or More
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
U. S. Government agencies and corporations	$	6,964	$	30	$	156,149	$	4,709
State and political subdivisions		1,222		35		19,818		692
Corporate debt securities		450		2		1,948		27
Other securities		---		---		127		62
Total temporarily impaired securities	$	8,636	$	67	$	178,042	$	5,490

The Company had 209 securities with a fair value of $192,125 that were temporarily impaired at December 31, 2015.  The total unrealized loss on these securities was $5,814. Of the temporarily impaired total, 106 securities with a fair value of $95,447 and an unrealized loss of $3,698 have been in a continuous loss position for twelve months or more. The Company has determined that these securities are temporarily impaired at December 31, 2015 for the reasons set out below.

U.S. Government agencies.   The unrealized losses of $5,129 on US Government agency securities stemmed from 178 securities with a fair value of $173,214. The unrealized losses were caused by interest rate and market fluctuations. The contractual terms of the investments do not permit the issuer to settle the securities at a price less than the cost basis of each investment. The Company is monitoring bond market trends and developing strategies to address unrealized losses. Because the Company does not intend to sell any of the investments and it is not likely that the Company will be required to sell any of the investments before recovery of its amortized cost basis, which may be at maturity, the Company does not consider these investments to be other-than-temporarily impaired.

States and political subdivisions. This category’s unrealized losses of $330 on 23 securities with a fair value of $13,610 are primarily the result of interest rate and market fluctuations. The contractual terms of the investments do not permit the issuer to settle the securities at a price less than the cost basis of each investment. Because the Company does not intend to sell any of the investments and it is not likely that the Company will be required to sell any of the investments before recovery of its amortized cost basis, which may be at maturity, the Company does not consider these investments to be other-than-temporarily impaired.

Corporate. The Company’s unrealized losses of $293 on 7 corporate debt securities with a fair value of $5,174 are related to interest rate and market fluctuations. The contractual terms of the investments do not permit the issuer to settle the securities at a price less than the cost basis of each investment. Because the Company does not intend to sell any of the investments before recovery of its amortized cost basis, which may be at maturity, the Company does not consider these investments to be other-than-temporarily impaired.

Other securities. The Company holds a small investment in community bank stock. One security with a fair value of $127 has an unrealized loss of $62. The value of this investment has been negatively affected by market conditions. Because the Company does not intend to sell this investment before recovery of its amortized cost basis, the Company does not consider this investment to be other-than-temporarily impaired.    

Restricted stock. Restricted stock is reported separately from available-for-sale securities and held-to-maturity securities. As a member of the Federal Reserve and the Federal Home Loan Bank (“FHLB”) of Atlanta, NBB is required to maintain certain minimum investments in the common stock of those entities. Required levels of investment are based upon NBB’s capital and a percentage of qualifying assets. In addition, NBB is eligible to borrow from the FHLB with borrowings collateralized by qualifying assets, primarily residential mortgage loans totaling approximately $440,062 at December 31, 2015, and NBB’s capital stock investment in the FHLB. Redemption of FHLB stock is subject to certain limitations and conditions. At its discretion, the FHLB may declare dividends on the stock. Management reviews for impairment based upon the ultimate recoverability of the cost basis of the FHLB stock, and at December 31, 2015, management did not determine any impairment.

Management regularly monitors the credit quality of the investment portfolio. Changes in ratings are noted and follow-up research on the issuer is undertaken when warranted. Management intends to carefully monitor any changes in bond quality.

At December 31, 2015 and 2014, securities with a carrying value of $156,721 and $157,951, respectively, were pledged to secure municipal deposits and for other purposes as required or permitted by law.