Investment Securities

The following table shows the amortized cost and the estimated fair value of the held-to-maturity securities and available-for-sale securities at March 31, 2017 and December 31, 2016, by contractual maturity within each type:



	At March 31, 2017									At December 31, 2016
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Securities Held-to-Maturity
U.S. government corporations and agencies:
After 1 year to 5 years	$	5,000	$	—	$	(8	)	$	4,992	$	—	$	—	$	—		$	—
	5,000		—		(8		)	4,992		—		—		—			—
Residential mortgage-backed securities:
After 5 years to 10 years	4,959		2		—			4,961		—		—		—			—
Over 10 years	13,066		16		(9		)	13,073		5,071		—		(3		)	5,068
	18,025		18		(9		)	18,034		5,071		—		(3		)	5,068
Corporate bonds:
Within 1 year	10,002		—		(6		)	9,996		19,810		2		(9		)	19,803
	10,002		—		(6		)	9,996		19,810		2		(9		)	19,803
Total	$	33,027	$	18	$	(23	)	$	33,022	$	24,881	$	2	$	(12	)	$	24,871
Securities Available-for-Sale
U.S. government corporations and agencies:
Within 1 year	$	15,000	$	6	$	—		$	15,006	$	15,000	$	20	$	—		$	15,020
After 1 year to 5 years	17,220		2		(24		)	17,198		17,265		—		(19		)	17,246
	32,220		8		(24		)	32,204		32,265		20		(19		)	32,266
State and political subdivisions:
Within 1 year	2,105		—		—			2,105		964		—		(1		)	963
After 1 year to 5 years	18,122		67		(24		)	18,165		18,705		38		(75		)	18,668
After 5 years to 10 years	54,737		955		(250		)	55,442		55,541		829		(426		)	55,944
Over 10 years	8,855		138		(79		)	8,914		12,663		226		(114		)	12,775
	83,819		1,160		(353		)	84,626		87,873		1,093		(616		)	88,350
Residential mortgage-backed securities:
After 1 year to 5 years	5,628		6		(46		)	5,588		6,086		—		(66		)	6,020
After 5 years to 10 years	31,927		1		(771		)	31,157		23,479		—		(622		)	22,857
Over 10 years	157,202		95		(3,663		)	153,634		174,388		99		(4,794		)	169,693
	194,757		102		(4,480		)	190,379		203,953		99		(5,482		)	198,570
Collateralized mortgage obligations:
Over 10 years	4,390		—		(89		)	4,301		4,659		—		(105		)	4,554
	4,390		—		(89		)	4,301		4,659		—		(105		)	4,554
Corporate bonds:
Within 1 year	7,032		—		(24		)	7,008		250		—		—			250
After 1 year to 5 years	29,773		61		(154		)	29,680		35,923		34		(241		)	35,716
After 5 years to 10 years	15,187		—		(396		)	14,791		15,193		—		(516		)	14,677
Over 10 years	60,000		—		(3,612		)	56,388		60,000		27		(2,472		)	57,555
	111,992		61		(4,186		)	107,867		111,366		61		(3,229		)	108,198
Money market mutual funds:
No stated maturity	11,294		—		—			11,294		10,784		—		—			10,784
	11,294		—		—			11,294		10,784		—		—			10,784
Equity securities:
No stated maturity	409		533		(1		)	941		411		504		—			915
	409		533		(1		)	941		411		504		—			915
Total	$	438,881	$	1,864	$	(9,133	)	$	431,612	$	451,311	$	1,777	$	(9,451	)	$	443,637

Expected maturities may differ from contractual maturities because debt issuers may have the right to call or prepay obligations without call or prepayment penalties and mortgage-backed securities typically prepay at a rate faster than contractually due. Unrealized losses in investment securities at March 31, 2017 and December 31, 2016 do not represent other-than-temporary impairments in management's judgment.

Securities with a carrying value of $355.3 million and $356.7 million at March 31, 2017 and December 31, 2016, respectively, were pledged to secure public deposits and other contractual obligations. In addition, securities of $1.4 million were pledged to secure credit derivatives and interest rate swaps at March 31, 2017 and December 31, 2016. See Note 10, "Derivative Instruments and Hedging Activities" for additional information.

The following table presents information related to sales of securities available-for-sale during the three months ended March 31, 2017 and 2016:



	Three Months Ended March 31,
(Dollars in thousands)	2017		2016
Securities available-for-sale:
Proceeds from sales	$	1,762	$	53,181
Gross realized gains on sales	15		106
Gross realized losses on sales	—		62
Tax expense related to net realized gains on sales	5		15

Management evaluates debt securities, which are comprised of U.S. government, government sponsored agencies, municipalities, corporate bonds and other issuers, for other-than-temporary impairment by considering the current economic conditions, the length of time and the extent to which the fair value has been less than cost, market interest rates and the credit rating of each security. The Corporation does not have the intent to sell the debt securities and believes it is more likely than not, that it will not have to sell the securities before recovery of their cost basis. The Corporation did not recognize any other-than-temporary impairment charges on debt securities for the three months ended March 31, 2017 and 2016.

At March 31, 2017 and December 31, 2016, there were no investments in any single non-federal issuer representing more than 10% of shareholders’ equity.

The following table shows the fair value of securities that were in an unrealized loss position at March 31, 2017 and December 31, 2016 by the length of time those securities were in a continuous loss position. For the investment securities in an unrealized loss position, the Corporation has concluded, based on its analysis, that the unrealized losses are primarily caused by the movement of interest rates and current market conditions. The contractual terms of these investments do not permit the issuer to settle the securities at a price less than the par value of the investment. It is more likely than not that the Corporation will not be required to sell the investment before a recovery of carrying value.



	Less than Twelve Months					Twelve Months or Longer					Total
(Dollars in thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
At March 31, 2017
Securities Held-to-Maturity
U.S. government corporations and agencies	$	4,992	$	(8	)	$	—	$	—		$	4,992	$	(8	)
Residential mortgage-backed securities	5,000		(9		)	—		—			5,000		(9		)
Corporate bonds	4,995		(6		)	—		—			4,995		(6		)
Total	$	14,987	$	(23	)	$	—	$	—		$	14,987	$	(23	)
Securities Available-for-Sale
U.S. government corporations and agencies	$	11,837	$	(24	)	$	—	$	—		$	11,837	$	(24	)
State and political subdivisions	22,082		(344		)	1,706		(9		)	23,788		(353		)
Residential mortgage-backed securities	180,647		(4,480		)	—		—			180,647		(4,480		)
Collateralized mortgage obligations	1,885		(14		)	2,416		(75		)	4,301		(89		)
Corporate bonds	66,728		(2,025		)	32,839		(2,161		)	99,567		(4,186		)
Equity securities	3		(1		)	—		—			3		(1		)
Total	$	283,182	$	(6,888	)	$	36,961	$	(2,245	)	$	320,143	$	(9,133	)
At December 31, 2016
Securities Held-to-Maturity
Residential mortgage-backed securities	$	5,068	$	(3	)	$	—	$	—		$	5,068	$	(3	)
Corporate bonds	9,779		(9		)	—		—			9,779		(9		)
Total	$	14,847	$	(12	)	$	—	$	—		$	14,847	$	(12	)
Securities Available-for-Sale
U.S. government corporations and agencies	$	11,850	$	(19	)	$	—	$	—		$	11,850	$	(19	)
State and political subdivisions	40,771		(610		)	423		(6		)	41,194		(616		)
Residential mortgage-backed securities	192,782		(5,482		)	—		—			192,782		(5,482		)
Collateralized mortgage obligations	2,012		(26		)	2,542		(79		)	4,554		(105		)
Corporate bonds	58,535		(1,333		)	33,104		(1,896		)	91,639		(3,229		)
Total	$	305,950	$	(7,470	)	$	36,069	$	(1,981	)	$	342,019	$	(9,451	)