SECURITIES

Amortized cost and estimated fair value of securities available for sale are as follows (in thousands):



	June 30, 2018
	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
Obligations of U.S. Government and U.S. Government sponsored enterprises	$	15,489	$	11	$	50	$	15,450
Mortgage-backed securities, residential	207,708		69		9,137		198,640
Obligations of states and political subdivisions	47,574		37		582		47,029
Corporate bonds and notes	249		1		—		250
SBA loan pools	3,832		—		44		3,788
Total	$	274,852	$	118	$	9,813	$	265,157



	December 31, 2017
	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
Obligations of U.S. Government and U.S. Government sponsored enterprises	$	15,492	$	20	$	21	$	15,491
Mortgage-backed securities, residential	224,939		136		5,166		219,909
Obligations of states and political subdivisions	52,928		355		151		53,132
Corporate bonds and notes	249		2		—		251
SBA loan pools	4,339		1		32		4,308
Total	$	297,947	$	514	$	5,370	$	293,091

Amortized cost and estimated fair value of securities held to maturity are as follows (in thousands):



	June 30, 2018
	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
Obligations of states and political subdivisions	$	1,481	$	—	$	—	$	1,481
Time deposits with other financial institutions	2,325		—		16		2,309
Total	$	3,806	$	—	$	16	$	3,790



	December 31, 2017
	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
Obligations of states and political subdivisions	$	1,946	$	—	$	—	$	1,946
Time deposits with other financial institutions	1,835		—		5		1,830
Total	$	3,781	$	—	$	5	$	3,776

The amortized cost and estimated fair value of debt securities are shown below by expected maturity. Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations with or without call or prepayment penalties. Securities not due at a single maturity date are shown separately (in thousands):



	June 30, 2018
	Available for Sale				Held to Maturity
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Within one year	$	16,875	$	16,873	$	884	$	882
After one, but within five years	19,459		19,347		2,689		2,675
After five, but within ten years	26,495		26,053		233		233
After ten years	483		456		—		—
	63,312		62,729		3,806		3,790
Mortgage-backed securities, residential	207,708		198,640		—		—
SBA loan pools	3,832		3,788		—		—
Total	$	274,852	$	265,157	$	3,806	$	3,790

The proceeds from sales and calls of securities resulting in gains or losses for the three months ended June 30, 2018 and 2017 are listed below (in thousands):



	2018		2017
Proceeds	$	—	$	540
Gross gains	—		12
Tax expense	—		4

The proceeds from sales and calls of securities resulting in gains or losses for the six months ended June 30, 2018 and 2017 are listed below (in thousands):



	2018		2017
Proceeds	$	—	$	540
Gross gains	—		12
Tax expense	—		4

The following tables summarize the investment securities available for sale with unrealized losses at June 30, 2018 and December 31, 2017 by aggregated major security type and length of time in a continuous unrealized loss position (in thousands):



	Less than 12 months				12 months or longer				Total
June 30, 2018	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Obligations of U.S. Government and U.S. Government sponsored enterprises	$	14,948	$	50	$	—	$	—	$	14,948	$	50
Mortgage-backed securities, residential	65,746		2,193		130,586		6,944		196,332		9,137
Obligations of states and political subdivisions	36,819		488		1,709		94		38,528		582
SBA loan pools	243		1		3,545		43		3,788		44
Total temporarily impaired securities	$	117,756	$	2,732	$	135,840	$	7,081	$	253,596	$	9,813



	Less than 12 months				12 months or longer				Total
December 31, 2017	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Obligations of U.S. Government and U.S. Government sponsored enterprises	$	14,982	$	21	$	—	$	—	$	14,982	$	21
Mortgage-backed securities, residential	83,562		1,013		131,165		4,153		214,727		5,166
Obligations of states and political subdivisions	20,526		133		271		18		20,797		151
SBA loan pools	3,937		32		—		—		3,937		32
Total temporarily impaired securities	$	123,007	$	1,199	$	131,436	$	4,171	$	254,443	$	5,370

Other-Than-Temporary Impairment

As of June 30, 2018, the majority of the Corporation’s unrealized losses in the investment securities portfolio related to mortgage-backed securities. At June 30, 2018, all of the unrealized losses related to mortgage-backed securities were issued by U.S. government sponsored entities, Fannie Mae and Freddie Mac. Because the decline in fair value is attributable to changes in interest rates and not credit quality, and because it is not likely that the Corporation will be required to sell these securities before their anticipated recovery, the Corporation does not consider these securities to be other-than-temporarily impaired at June 30, 2018.