4. INVESTMENT SECURITIES

The following tables detail the amortized cost and the estimated fair value of our investments in available-for-sale and held-to-maturity debt securities as well as our equity investments. None of our investments in debt securities are classified as trading.



	September 30, 2018
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Available-for-Sale Debt Securities
CMO	$	311,507	$	—	$	11,477	$	300,030
FNMA MBS	571,686		—		22,948		548,738
FHLMC MBS	116,532		2		4,112		112,422
GNMA MBS	37,180		72		1,311		35,941
	$	1,036,905	$	74	$	39,848	$	997,131
Held-to-Maturity Debt Securities⁽¹⁾
State and political subdivisions	$	152,577	$	55	$	2,049	$	150,583

Equity Investments⁽²⁾
Visa Class B shares	$	13,918	$	17,865	$	—	$	31,783
Other equity investments	3,300		—		—		3,300
	$	17,218	$	17,865	$	—	$	35,083


⁽¹⁾	Held-to–maturity securities transferred from available-for-sale are included in held-to-maturity at fair value at the time of transfer. The amortized cost of held-to-maturity securities included net unrealized gains of $1.2 million at September 30, 2018, related to securities transferred, which are offset in Accumulated other comprehensive loss, net of tax.


⁽²⁾	Equity investments are included in Other investments in the unaudited Consolidated Statements of Financial Condition.



	December 31, 2017
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Available-for-Sale Debt Securities
CMO	$	250,592	$	88	$	4,141	$	246,539
FNMA MBS	479,218		941		6,172		473,987
FHLMC MBS	88,681		118		924		87,875
GNMA MBS	29,300		209		411		29,098
	$	847,791	$	1,356	$	11,648	$	837,499
Held-to-Maturity Debt Securities⁽¹⁾
State and political subdivisions	$	161,186	$	1,758	$	91	$	162,853

Equity Investments⁽²⁾⁽³⁾
Other equity investments	$	643	$	—	$	20	$	623
	$	643	$	—	$	20	$	623


⁽¹⁾	Held-to–maturity securities transferred from available-for-sale are included in held-to-maturity at fair value at the time of transfer. The amortized cost of held-to-maturity securities included net unrealized gains of $1.6 million at December 31, 2017, related to securities transferred, which are offset in Accumulated other comprehensive loss, net of tax.


⁽²⁾	Equity investments are included in Other investments in the unaudited Consolidated Statements of Financial Condition.


⁽³⁾	These municipal securities were sold during the second quarter of 2018.

The scheduled maturities of our available-for-sale debt securities at September 30, 2018 and December 31, 2017 are presented in the table below:



	Available for Sale
	Amortized		Fair
(Dollars in thousands)	Cost		Value
September 30, 2018
Within one year	$	—	$	—
After one year but within five years	19,792		19,160
After five years but within ten years	170,009		159,754
After ten years	847,104		818,217
	$	1,036,905	$	997,131
December 31, 2017
Within one year	$	—	$	—
After one year but within five years	20,051		19,825
After five years but within ten years	179,812		175,583
After ten years	647,928		642,091
	$	847,791	$	837,499

The scheduled maturities of our held-to-maturity debt securities at September 30, 2018 and December 31, 2017 are presented in the table below:



	Held to Maturity
	Amortized		Fair
(Dollars in thousands)	Cost		Value
September 30, 2018
Within one year	$	1,027	$	1,023
After one year but within five years	6,636		6,599
After five years but within ten years	29,148		28,902
After ten years	115,766		114,059
	$	152,577	$	150,583
December 31, 2017
Within one year	$	322	$	320
After one year but within five years	5,895		5,894
After five years but within ten years	18,751		18,873
After ten years	136,218		137,766
	$	161,186	$	162,853

Mortgage-backed securities (MBS) may have expected maturities that differ from their contractual maturities. These differences arise because issuers may have the right to call securities and borrowers may have the right to prepay obligations with or without prepayment penalty.

Investment securities with fair market values aggregating $972.8 million and $688.2 million were pledged as collateral for retail customer repurchase agreements, municipal deposits, and other obligations as of September 30, 2018 and December 31, 2017, respectively.

During the nine months ended September 30, 2018, we sold $7.0 million of debt securities categorized as available for sale, resulting in realized gains of less than $0.1 million and no realized losses. During the nine months ended September 30, 2017, we sold $415.5 million of debt securities categorized as available for sale, resulting in realized gains of $1.9 million and realized losses of less than $0.1 million. The cost basis of all debt securities sales is based on the specific identification method.

During the nine months ended September 30, 2018, we sold $6.2 million of equity securities, specifically Visa Class B shares, resulting in realized gains of $3.8 million and no realized losses. There were no such sales during the nine months ended September 30, 2017.

As of September 30, 2018 and December 31, 2017, our debt securities portfolio had remaining unamortized premiums of $12.8 million and $14.1 million, respectively, and unaccreted discounts of $1.8 million and $1.3 million as of September 30, 2018 and December 31, 2017.

For debt securities with unrealized losses, the table below shows our gross unrealized losses and fair value by investment category and length of time that individual debt securities were in a continuous unrealized loss position at September 30, 2018.



	Duration of Unrealized Loss Position
	Less than 12 months				12 months or longer				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(Dollars in thousands)	Value		Loss		Value		Loss		Value		Loss
Available-for-sale debt securities:
CMO	$	138,346	$	2,826	$	161,684	$	8,651	$	300,030	$	11,477
FNMA MBS	303,994		8,047		244,744		14,901		548,738		22,948
FHLMC MBS	55,386		1,271		52,514		2,841		107,900		4,112
GNMA MBS	19,329		504		13,419		807		32,748		1,311
Total temporarily impaired investments	$	517,055	$	12,648	$	472,361	$	27,200	$	989,416	$	39,848

Held-to-maturity debt securities:
State and political subdivisions	$	150,060	$	2,013	$	523	$	36	$	150,583	$	2,049
Total temporarily impaired investments	$	150,060	$	2,013	$	523	$	36	$	150,583	$	2,049

For debt investment securities with unrealized losses, the table below shows our gross unrealized losses and fair value by investment category and length of time that individual debt securities were in a continuous unrealized loss position at December 31, 2017.



	Duration of Unrealized Loss Position
	Less than 12 months				12 months or longer				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(Dollars in thousands)	Value		Loss		Value		Loss		Value		Loss
Available-for-sale debt securities:
CMO	$	146,726	$	1,820	$	77,149	$	2,321	$	223,875	$	4,141
FNMA MBS	204,921		1,479		126,342		4,693		331,263		6,172
FHLMC MBS	42,514		269		21,405		655		63,919		924
GNMA MBS	4,615		56		14,782		355		19,397		411
Total temporarily impaired investments	$	398,776	$	3,624	$	239,678	$	8,024	$	638,454	$	11,648

Held-to-maturity debt securities:
State and political subdivisions	$	23,404	$	59	$	5,625	$	32	$	29,029	$	91
Total temporarily impaired investments	$	23,404	$	59	$	5,625	$	32	$	29,029	$	91

Other equity investments	$	—	$	—	$	624	$	20	$	624	$	20

At September 30, 2018, we owned debt securities totaling $1.1 billion for which the amortized cost basis exceeded fair value. Total unrealized losses on these securities were $41.9 million at September 30, 2018. The temporary impairment is the result of changes in market interest rates subsequent to purchase. Our investment portfolio is reviewed each quarter for indications of OTTI. This review includes analyzing the length of time and the extent to which the fair value has been lower than the amortized cost, the financial condition and near-term prospects of the issuer, including any specific events which may influence the operations of the issuer and our intent and ability to hold the investment for a period of time sufficient to allow for full recovery of the unrealized loss. We evaluate our intent and ability to hold debt securities based upon our investment strategy for the particular type of security and our cash flow needs, liquidity position, capital adequacy and interest rate risk position. We do not have the intent to sell, nor is it more likely-than-not we will be required to sell these securities before we are able to recover the amortized cost basis.

All debt securities, with the exception of one having a fair value of $0.6 million at September 30, 2018, were AA-rated or better at the time of purchase and remained investment grade at September 30, 2018. All securities were evaluated for OTTI at September 30, 2018 and December 31, 2017. The result of this evaluation showed no OTTI as of September 30, 2018 or December 31, 2017. The estimated weighted average duration of MBS was 5.6 years at September 30, 2018.