Investment Securities

The following table presents the amortized costs, unrealized gains, unrealized losses and approximate fair values of investment securities at June 30, 2014 and December 31, 2013:



(in thousands)	June 30, 2014
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
AVAILABLE FOR SALE:
U.S. Treasury and agencies	$	214	$	19	$	—		$	233
Obligations of states and political subdivisions	336,607		13,428		(1,056		)	348,979
Residential mortgage-backed securities and collateralized mortgage obligations	2,229,391		22,995		(14,645		)	2,237,741
Investments in mutual funds and other equity securities	2,016		—		—			2,016
	$	2,568,228	$	36,442	$	(15,701	)	$	2,588,969
HELD TO MATURITY:
Residential mortgage-backed securities and collateralized mortgage obligations	$	5,375	$	306	$	(42	)	$	5,639
Other investment securities	144		—		—			144
	$	5,519	$	306	$	(42	)	$	5,783



(in thousands)	December 31, 2013
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
AVAILABLE FOR SALE:
U.S. Treasury and agencies	$	249	$	20	$	(1	)	$	268
Obligations of states and political subdivisions	229,969		7,811		(2,575		)	235,205
Residential mortgage-backed securities and collateralized mortgage obligations	1,567,001		15,359		(28,819		)	1,553,541
Investments in mutual funds and other equity securities	1,959		5		—			1,964
	$	1,799,178	$	23,195	$	(31,395	)	$	1,790,978
HELD TO MATURITY:
Residential mortgage-backed securities and collateralized mortgage obligations	$	5,563	$	330	$	(19	)	$	5,874
	$	5,563	$	330	$	(19	)	$	5,874

Investment securities that were in an unrealized loss position as of June 30, 2014 and December 31, 2013 are presented in the following tables, based on the length of time individual securities have been in an unrealized loss position. In the opinion of management, these securities are considered only temporarily impaired due to changes in market interest rates or the widening of market spreads subsequent to the initial purchase of the securities, and not due to concerns regarding the underlying credit of the issuers or the underlying collateral.



June 30, 2014
(in thousands)	Less than 12 Months				12 Months or Longer				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
AVAILABLE FOR SALE:
Obligations of states and political subdivisions	$	7,145	$	647	$	24,892	$	409	$	32,037	$	1,056
Residential mortgage-backed securities and collateralized mortgage obligations	249,624		582		557,774		14,063		807,398		14,645
Total temporarily impaired securities	$	256,769	$	1,229	$	582,666	$	14,472	$	839,435	$	15,701
HELD TO MATURITY:
Residential mortgage-backed securities and collateralized mortgage obligations	$	210	$	42	$	—	$	—	$	210	$	42
Total temporarily impaired securities	$	210	$	42	$	—	$	—	$	210	$	42

Unrealized losses on the impaired held to maturity collateralized mortgage obligations include the unrealized losses related to factors other than credit that are included in other comprehensive income.



December 31, 2013
(in thousands)	Less than 12 Months				12 Months or Longer				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
AVAILABLE FOR SALE:
U.S. Treasury and agencies	$	—	$	—	$	32	$	1	$	32	$	1
Obligations of states and political subdivisions	48,342		2,575		—		—		48,342		2,575
Residential mortgage-backed securities and collateralized mortgage obligations	475,982		15,951		249,695		12,868		725,677		28,819
Total temporarily impaired securities	$	524,324	$	18,526	$	249,727	$	12,869	$	774,051	$	31,395
HELD TO MATURITY:
Residential mortgage-backed securities and collateralized mortgage obligations	$	156	$	19	$	—	$	—	$	156	$	19
Total temporarily impaired securities	$	156	$	19	$	—	$	—	$	156	$	19

The unrealized losses on investments in U.S. Treasury and agency securities were caused by interest rate increases subsequent to the purchase of these securities. The contractual terms of these investments do not permit the issuer to settle the securities at a price less than par. Because the Bank does not intend to sell the securities in this class and it is not likely that the Bank will be required to sell these securities before recovery of their amortized cost basis, which may include holding each security until contractual maturity, the unrealized losses on these investments are not considered other-than-temporarily impaired ("OTTI").

The unrealized losses on obligations of political subdivisions were caused by changes in market interest rates or the widening of market spreads subsequent to the initial purchase of these securities. Management monitors published credit ratings of these securities and no adverse ratings changes have occurred since the date of purchase of obligations of political subdivisions which are in an unrealized loss position as of June 30, 2014. Because the decline in fair value is attributable to changes in interest rates or widening market spreads and not credit quality, and because the Bank does not intend to sell the securities in this class and it is not likely that the Bank will be required to sell these securities before recovery of their amortized cost basis, which may include holding each security until maturity, the unrealized losses on these investments are not considered OTTI.

All of the available for sale residential mortgage-backed securities and collateralized mortgage obligations portfolio in an unrealized loss position at June 30, 2014 are issued or guaranteed by governmental agencies. The unrealized losses on residential mortgage-backed securities and collateralized mortgage obligations were caused by changes in market interest rates or the widening of market spreads subsequent to the initial purchase of these securities, and not concerns regarding the underlying credit of the issuers or the underlying collateral. It is expected that these securities will not be settled at a price less than the amortized cost of each investment. Because the decline in fair value is attributable to changes in interest rates or widening market spreads and not credit quality, and because the Bank does not intend to sell the securities in this class and it is not likely that the Bank will be required to sell these securities before recovery of their amortized cost basis, which may include holding each security until contractual maturity, these investments are not considered OTTI.

The following table presents the maturities of investment securities at June 30, 2014:



(in thousands)	Available For Sale				Held To Maturity
	Amortized		Fair		Amortized		Fair
	Cost		Value		Cost		Value
AMOUNTS MATURING IN:
Three months or less	$	11,267	$	11,314	$	—	$	—
Over three months through twelve months	40,413		40,990		5		5
After one year through five years	1,522,689		1,548,906		27		28
After five years through ten years	887,929		879,608		29		31
After ten years	103,914		106,135		5,314		5,575
Other investment securities	2,016		2,016		144		144
	$	2,568,228	$	2,588,969	$	5,519	$	5,783

The amortized cost and fair value of collateralized mortgage obligations and mortgage-backed securities are presented by expected average life, rather than contractual maturity, in the preceding table. Expected maturities may differ from contractual maturities because borrowers have the right to prepay underlying loans without prepayment penalties. The following table presents the gross realized gains and gross realized losses on the sale of securities available for sale for the three and six months ended June 30, 2014 and 2013:



(in thousands)	Three Months Ended
	June 30, 2014				June 30, 2013
	Gains		Losses		Gains		Losses
Obligations of states and political subdivisions	$	3	$	1	$	—	$	1
Residential mortgage-backed securities and collateralized mortgage obligations	974		—		—		—
Other debt securities	—		—		9		—
	$	977	$	1	$	9	$	1

	Six Months Ended
	June 30, 2014				June 30, 2013
	Gains		Losses		Gains		Losses
Obligations of states and political subdivisions	$	3	$	1	$	7	$	1
Residential mortgage-backed securities and collateralized mortgage obligations	974		—		—		—
Other debt securities	—		—		9		—
	$	977	$	1	$	16	$	1

The following table presents, as of June 30, 2014, investment securities which were pledged to secure borrowings, public deposits, and repurchase agreements as permitted or required by law:



(in thousands)	Amortized		Fair
	Cost		Value
To Federal Home Loan Bank to secure borrowings	$	8,290	$	8,634
To state and local governments to secure public deposits	1,674,935		1,687,353
Other securities pledged principally to secure repurchase agreements	460,240		459,421
Total pledged securities	$	2,143,465	$	2,155,408