INVESTMENT SECURITIES

A summary of held-to-maturity and available-for-sale investment securities are as follows:



(dollars in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
September 30, 2016
Held-to-Maturity:
Mortgage-backed securities:
Residential - U.S. Government-sponsored entities	$	132,470	$	890	$	(2	)	$	133,358
Commercial - U.S. Government-sponsored entities	94,103		3,068		—			97,171
Total	$	226,573	$	3,958	$	(2	)	$	230,529

Available-for-Sale:
Debt securities:
States and political subdivisions	$	185,504	$	6,300	$	(26	)	$	191,778
Corporate securities	107,011		2,609		(12		)	109,608
Mortgage-backed securities:
Residential - U.S. Government-sponsored entities	747,636		11,881		(314		)	759,203
Residential - Non-government agencies	55,480		2,142		—			57,622
Commercial - Non-government agencies	135,296		7,933		—			143,229
Other	692		92		—			784
Total	$	1,231,619	$	30,957	$	(352	)	$	1,262,224



(dollars in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
December 31, 2015
Held-to-Maturity:
Mortgage-backed securities:
Residential - U.S. Government-sponsored entities	$	152,315	$	123	$	(2,915	)	$	149,523
Commercial - U.S. Government-sponsored entities	95,602		—		(989		)	94,613
Total	$	247,917	$	123	$	(3,904	)	$	244,136

Available-for-Sale:
Debt securities:
States and political subdivisions	$	187,552	$	3,819	$	(898	)	$	190,473
Corporate securities	107,721		1,077		(227		)	108,571
Mortgage-backed securities:
Residential - U.S. Government-sponsored entities	771,657		5,885		(5,633		)	771,909
Residential - Non-government agencies	64,286		733		(987		)	64,032
Commercial - Non-government agencies	135,439		2,033		(1,118		)	136,354
Other	848		68		—			916
Total	$	1,267,503	$	13,615	$	(8,863	)	$	1,272,255

The amortized cost and estimated fair value of investment securities at September 30, 2016 by contractual maturity are shown below. Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties.



	September 30, 2016
(dollars in thousands)	Amortized Cost		Estimated Fair Value
Held-to-Maturity:
Mortgage-backed securities:
Residential - U.S. Government-sponsored entities	$	132,470	$	133,358
Commercial - U.S. Government-sponsored entities	94,103		97,171
Total	$	226,573	$	230,529

Available-for-Sale:
Due in one year or less	$	13,648	$	13,676
Due after one year through five years	124,029		127,061
Due after five years through ten years	73,338		75,987
Due after ten years	81,500		84,662

Mortgage-backed securities:
Residential - U.S. Government-sponsored entities	747,636		759,203
Residential - Non-government agencies	55,480		57,622
Commercial - Non-government agencies	135,296		143,229
Other	692		784
Total	$	1,231,619	$	1,262,224

We did not sell any available-for-sale securities during the nine months ended September 30, 2016.

During the second quarter of 2015, we sold certain available-for-sale investment securities for gross proceeds of $117.5 million. Gross realized losses on the sale of the available-for-sale investment securities were $1.9 million. The specific identification method was used as the basis for determining the cost of all securities sold. We did not sell any available-for-sale securities during the first and third quarters of 2015.

Investment securities of $1.10 billion and $1.00 billion at September 30, 2016 and December 31, 2015, respectively, were pledged to secure public funds on deposit and other long-term debt and short-term borrowings.

Provided below is a summary of the 21 and 155 investment securities which were in an unrealized loss position at September 30, 2016 and December 31, 2015, respectively, segregated by continuous length of impairment.



	Less Than 12 Months					12 Months or Longer					Total
(dollars in thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
September 30, 2016
Debt securities:
States and political subdivisions	$	3,425	$	(26	)	$	—	$	—		$	3,425	$	(26	)
Corporate securities	5,497		(12		)	—		—			5,497		(12		)
Mortgage-backed securities:
Residential - U.S. Government-sponsored entities	101,566		(263		)	4,181		(53		)	105,747		(316		)
Total temporarily impaired securities	$	110,488	$	(301	)	$	4,181	$	(53	)	$	114,669	$	(354	)



	Less Than 12 Months					12 Months or Longer					Total
(dollars in thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
December 31, 2015
Debt securities:
States and political subdivisions	$	30,481	$	(532	)	$	12,576	$	(366	)	$	43,057	$	(898	)
Corporate securities	32,977		(227		)	—		—			32,977		(227		)
Mortgage-backed securities:
Residential - U.S. Government-sponsored entities	507,525		(6,241		)	88,271		(2,307		)	595,796		(8,548		)
Residential - Non-government agencies	37,975		(987		)	—		—			37,975		(987		)
Commercial - U.S. Government-sponsored entities	94,613		(989		)	—		—			94,613		(989		)
Commercial - Non-government agencies	62,555		(961		)	4,644		(157		)	67,199		(1,118		)
Total temporarily impaired securities	$	766,126	$	(9,937	)	$	105,491	$	(2,830	)	$	871,617	$	(12,767	)

Other-Than-Temporary Impairment (“OTTI”)

Unrealized losses for all investment securities are reviewed to determine whether the losses are deemed “other-than-temporary.” Investment securities are evaluated for OTTI on at least a quarterly basis and more frequently when economic or market conditions warrant such an evaluation to determine whether a decline in their value below amortized cost is other-than-temporary. In conducting this assessment, we evaluate a number of factors including, but not limited to:


•	The length of time and the extent to which fair value has been less than the amortized cost basis;


•	Adverse conditions specifically related to the security, an industry, or a geographic area;


•	The historical and implied volatility of the fair value of the security;


•	The payment structure of the debt security and the likelihood of the issuer being able to make payments;


•	Failure of the issuer to make scheduled interest or principal payments;


•	Any rating changes by a rating agency; and


•	Recoveries or additional declines in fair value subsequent to the balance sheet date.

The term “other-than-temporary” is not intended to indicate that the decline is permanent, but indicates that the prospects for a near-term recovery of value are not necessarily favorable, or that there is a general lack of evidence to support a realizable value equal to or greater than the carrying value of the investment. Once a decline in value is determined to be other-than-temporary, the value of the security is reduced and a corresponding charge to earnings is recognized for anticipated credit losses.

Because we have no intent to sell securities in an unrealized loss position and it is not more likely than not that we will be required to sell such securities before recovery of its amortized cost basis, we do not consider our investments to be other-than-temporarily impaired.