(4.)INVESTMENT SECURITIES

The amortized cost and fair value of investment securities are summarized below (in thousands):

	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
June 30, 2018
Securities available for sale:
U.S. Government agency and government sponsored enterprises	$	162,330	$	11	$	4,815	$	157,526
Mortgage-backed securities:
Federal National Mortgage Association		296,084		52		9,954		286,182
Federal Home Loan Mortgage Corporation		38,387		15		1,655		36,747
Government National Mortgage Association		10,595		140		102		10,633
Collateralized mortgage obligations:
Federal National Mortgage Association		163		—		—		163
Federal Home Loan Mortgage Corporation		40		—		—		40
Privately issued		—		937		—		937
Total mortgage-backed securities		345,269		1,144		11,711		334,702
Total available for sale securities	$	507,599	$	1,155	$	16,526	$	492,228
Securities held to maturity:
State and political subdivisions		250,791		1,287		1,559		250,519
Mortgage-backed securities:
Federal National Mortgage Association		10,574		—		340		10,234
Federal Home Loan Mortgage Corporation		4,662		—		226		4,436
Government National Mortgage Association		33,934		13		954		32,993
Collateralized mortgage obligations:
Federal National Mortgage Association		68,906		—		2,966		65,940
Federal Home Loan Mortgage Corporation		85,824		—		3,705		82,119
Government National Mortgage Association		20,112		—		811		19,301
Total mortgage-backed securities		224,012		13		9,002		215,023
Total held to maturity securities	$	474,803	$	1,300	$	10,561	$	465,542
December 31, 2017
Securities available for sale:
U.S. Government agency and government sponsored enterprises	$	163,025	$	122	$	1,258	$	161,889
Mortgage-backed securities:
Federal National Mortgage Association		311,830		313		3,220		308,923
Federal Home Loan Mortgage Corporation		41,290		76		675		40,691
Government National Mortgage Association		12,051		193		12		12,232
Collateralized mortgage obligations:
Federal National Mortgage Association		217		1		1		217
Federal Home Loan Mortgage Corporation		45		—		—		45
Privately issued		—		976		—		976
Total mortgage-backed securities		365,433		1,559		3,908		363,084
Total available for sale securities	$	528,458	$	1,681	$	5,166	$	524,973

(4.)INVESTMENT SECURITIES (Continued)

	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
December 31, 2017 (continued)
Securities held to maturity:
State and political subdivisions		283,557		2,317		662		285,212
Mortgage-backed securities:
Federal National Mortgage Association		9,732		16		88		9,660
Federal Home Loan Mortgage Corporation		3,213		—		119		3,094
Government National Mortgage Association		26,841		—		330		26,511
Collateralized mortgage obligations:
Federal National Mortgage Association		76,432		—		1,958		74,474
Federal Home Loan Mortgage Corporation		93,810		3		2,165		91,648
Government National Mortgage Association		22,881		5		502		22,384
Total mortgage-backed securities		232,909		24		5,162		227,771
Total held to maturity securities	$	516,466	$	2,341	$	5,824	$	512,983

Investment securities with a total fair value of $813.5 million and $838.4 million at June 30, 2018 and December 31, 2017, respectively, were pledged as collateral to secure public deposits and for other purposes required or permitted by law.

Sales and calls of securities available for sale were as follows (in thousands):

	Three months ended June 30,				Six months ended June 30,
	2018		2017		2018		2017
Proceeds from sales	$	5,768	$	12,957	$	5,768	$	25,307
Gross realized gains		9		210		9		416
Gross realized losses		2		—		2		—

The scheduled maturities of securities available for sale and securities held to maturity at June 30, 2018 are shown below (in thousands). Actual expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations.

	Amortized		Fair
	Cost		Value
Debt securities available for sale:
Due in one year or less	$	26,364	$	26,197
Due from one to five years		144,174		140,856
Due after five years through ten years		238,443		229,545
Due after ten years		98,618		95,630
	$	507,599	$	492,228
Debt securities held to maturity:
Due in one year or less	$	55,989	$	56,177
Due from one to five years		151,052		151,799
Due after five years through ten years		88,698		85,681
Due after ten years		179,064		171,885
	$	474,803	$	465,542

(4.)INVESTMENT SECURITIES (Continued)

Unrealized losses on investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, were as follows (in thousands):

	Less than 12 months				12 months or longer				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
June 30, 2018
Securities available for sale:
U.S. Government agency and government sponsored enterprises	$	123,345	$	3,328	$	30,701	$	1,487	$	154,046	$	4,815
Mortgage-backed securities:
Federal National Mortgage Association		219,797		7,637		63,598		2,317		283,395		9,954
Federal Home Loan Mortgage Corporation		21,415		751		14,438		904		35,853		1,655
Government National Mortgage Association		4,410		97		789		5		5,199		102
Collateralized mortgage obligations:
Federal National Mortgage Association		—		—		77		—		77		—
Federal Home Loan Mortgage Corporation		—		—		7		—		7		—
Total mortgage-backed securities		245,622		8,485		78,909		3,226		324,531		11,711
Total available for sale securities		368,967		11,813		109,610		4,713		478,577		16,526
Securities held to maturity:
State and political subdivisions		65,548		883		15,698		676		81,246		1,559
Mortgage-backed securities:
Federal National Mortgage Association		7,662		202		2,572		138		10,234		340
Federal Home Loan Mortgage Corporation		1,474		13		2,962		213		4,436		226
Government National Mortgage Association		11,967		399		13,627		555		25,594		954
Collateralized mortgage obligations:
Federal National Mortgage Association		16,268		500		49,672		2,466		65,940		2,966
Federal Home Loan Mortgage Corporation		20,606		799		61,513		2,906		82,119		3,705
Government National Mortgage Association		6,940		282		12,361		529		19,301		811
Total mortgage-backed securities		64,917		2,195		142,707		6,807		207,624		9,002
Total held to maturity securities		130,465		3,078		158,405		7,483		288,870		10,561
Total temporarily impaired securities	$	499,432	$	14,891	$	268,015	$	12,196	$	767,447	$	27,087
December 31, 2017
Securities available for sale:
U.S. Government agencies and government sponsored enterprises	$	95,046	$	571	$	31,561	$	687	$	126,607	$	1,258
Mortgage-backed securities:
Federal National Mortgage Association		201,754		1,855		67,383		1,365		269,137		3,220
Federal Home Loan Mortgage Corporation		20,446		192		15,601		483		36,047		675
Government National Mortgage Association		2,432		—		880		12		3,312		12
Collateralized mortgage obligations:
Federal National Mortgage Association		—		—		119		1		119		1
Federal Home Loan Mortgage Corporation		—		—		8		—		8		—
Total mortgage-backed securities		224,632		2,047		83,991		1,861		308,623		3,908
Total available for sale securities		319,678		2,618		115,552		2,548		435,230		5,166

(4.)INVESTMENT SECURITIES (Continued)

	Less than 12 months				12 months or longer				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
December 31, 2017 (continued)
Securities held to maturity:
State and political subdivisions		36,368		295		14,492		367		50,860		662
Mortgage-backed securities:
Federal National Mortgage Association		3,766		29		2,694		59		6,460		88
Federal Home Loan Mortgage Corporation		—		—		3,094		119		3,094		119
Government National Mortgage Association		17,327		136		9,184		194		26,511		330
Collateralized mortgage obligations:
Federal National Mortgage Association		16,830		202		57,645		1,756		74,475		1,958
Federal Home Loan Mortgage Corporation		23,727		337		66,467		1,828		90,194		2,165
Government National Mortgage Association		15,401		340		5,635		162		21,036		502
Total mortgage-backed securities		77,051		1,044		144,719		4,118		221,770		5,162
Total held to maturity securities		113,419		1,339		159,211		4,485		272,630		5,824
Total temporarily impaired securities	$	433,097	$	3,957	$	274,763	$	7,033	$	707,860	$	10,990

The total number of security positions in the investment portfolio in an unrealized loss position at June 30, 2018 was 563 compared to 411 at December 31, 2017. At June 30, 2018, the Company had positions in 187 investment securities with a fair value of $268.0 million and a total unrealized loss of $12.2 million that have been in a continuous unrealized loss position for more than 12 months. At June 30, 2018, there were a total of 376 securities positions in the Company’s investment portfolio with a fair value of $499.4 million and a total unrealized loss of $14.9 million that had been in a continuous unrealized loss position for less than 12 months. At December 31, 2017, the Company had positions in 172 investment securities with a fair value of $274.8 million and a total unrealized loss of $7.0 million that had been in a continuous unrealized loss position for more than 12 months. At December 31, 2017, there were a total of 239 securities positions in the Company’s investment portfolio with a fair value of $433.1 million and a total unrealized loss of $4.0 million that had been in a continuous unrealized loss position for less than 12 months. The unrealized loss on investment securities was predominantly caused by changes in market interest rates subsequent to purchase. The fair value of most of the investment securities in the Company’s portfolio fluctuates as market interest rates change.

The Company reviews investment securities on an ongoing basis for the presence of other than temporary impairment (“OTTI”) with formal reviews performed quarterly. When evaluating debt securities for OTTI, management considers many factors, including: (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near-term prospects of the issuer, (3) whether the market decline was affected by macroeconomic conditions, and (4) whether the Company has the intention to sell the debt security or whether it is more likely than not that it will be required to sell the debt security before its anticipated recovery. The assessment of whether OTTI exists involves a high degree of subjectivity and judgment and is based on the information then available to management. There was no impairment recorded during the six months ended June 30, 2018 and 2017.

Based on management’s review and evaluation of the Company’s debt securities as of June 30, 2018, the debt securities with unrealized losses were not considered to be OTTI. As of June 30, 2018, the Company did not intend to sell any of the securities in a loss position and believes that it is not likely that it will be required to sell any such securities before the anticipated recovery of amortized cost. Accordingly, as of June 30, 2018, management has concluded that unrealized losses on its investment securities are temporary and no further impairment loss has been realized in the Company’s consolidated statements of income.