5.	INVESTMENT SECURITIES

The amortized cost and estimated fair value of investment securities are summarized below. The majority of securities held are traded in markets where similar assets are actively traded. Estimated fair values were obtained from an independent pricing service based upon market quotes.


	December 31, 2017
	Amortized Cost		Gross Unrealized Holding Gain		Gross Unrealized Holding Loss		Fair Value		Total Percent
	(Dollars in thousands)
Investment securities available-for-sale:
Residential mortgage-backed securities	$	1,747,780	$	11,231	$	(8,102)	$	1,750,909		84.14%
CMO/REMIC - residential		274,634		1,277		(2,082)		273,829		13.16%
Municipal bonds		54,966		774		(244)		55,496		2.66%
Other securities		751		-		-		751		0.04%

Total available-for-sale securities	$	2,078,131	$	13,282	$	(10,428)	$	2,080,985		100.00%

Investment securities held-to-maturity:
Government agency/GSE	$	159,716	$	854	$	(2,134)	$	158,436		19.25%
Residential mortgage-backed securities		176,427		667		(382)		176,712		21.26%
CMO		225,072		-		(8,641)		216,431		27.12%
Municipal bonds		268,675		2,751		(3,790)		267,636		32.37%

Total held-to-maturity securities	$	829,890	$	4,272	$	(14,947)	$	819,215		100.00%


	December 31, 2016
	Amortized Cost		Gross Unrealized Holding Gain		Gross Unrealized Holding Loss		Fair Value		Total Percent
	(Dollars in thousands)
Investment securities available-for-sale:
Government agency/GSE	$	2,750	$	2	$	-	$	2,752		0.12%
Residential mortgage-backed securities		1,822,168		18,812		(6,232)		1,834,748		80.81%
CMO/REMIC - residential		345,313		3,361		(1,485)		347,189		15.29%
Municipal bonds		80,137		889		(955)		80,071		3.53%
Other securities		5,506		200		-		5,706		0.25%

Total available-for-sale securities	$	2,255,874	$	23,264	$	(8,672)	$	2,270,466		100.00%

Investment securities held-to-maturity:
Government agency/GSE	$	182,648	$	362	$	(1,972)	$	181,038		20.03%
Residential mortgage-backed securities		193,699		-		(1,892)		191,807		21.25%
CMO		244,419		-		(6,808)		237,611		26.81%
Municipal bonds		290,910		776		(4,768)		286,918		31.91%

Total held-to-maturity securities	$	911,676	$	1,138	$	(15,440)	$	897,374		100.00%

The following table provides information about the amount of interest income earned on investment securities which is fully taxable and which is exempt from regular federal income tax.


	For the Year Ended December 31,
	2017		2016		2015
	(Dollars in thousands)
Investment securities available-for-sale:
Taxable	$	47,596	$	43,538	$	48,854
Tax-advantaged		2,182		4,164		14,336

Total interest income from available-for-sale securities		49,778		47,702		63,190

Investment securities held-to-maturity:
Taxable		12,558		10,183		4,451
Tax-advantaged		8,457		10,044		4,567

Total interest income from held-to-maturity securities		21,015		20,227		9,018

Total interest income from investment securities	$	70,793	$	67,929	$	72,208

Approximately 89% of the total investment securities portfolio at December 31, 2017 represents securities issued by the U.S government or U.S. government-sponsored enterprises, with the implied guarantee of payment of principal and interest. All non-agency available-for-saleCollateralized Mortgage Obligations (“CMO”)/Real Estate Mortgage Investment Conduit (“REMIC”) issues held are rated investment grade or better by either Standard & Poor’s or Moody’s, as of December 31, 2017 and 2016.

The tables below show the Company’s investment securities’ gross unrealized losses and fair value by investment category and length of time that individual securities have been in a continuous unrealized loss position at December 31, 2017 and 2016. Management has reviewed individual securities to determine whether a decline in fair value below the amortized cost basis is other-than-temporary. The unrealized losses on these securities were primarily attributed to changes in interest rates. The issuers of these securities have not, to our knowledge, evidenced any cause for default on these securities. These securities have fluctuated in value since their purchase dates as market rates have fluctuated. However, we have the ability and the intention to hold these securities until their fair values recover to cost or maturity. As such, management does not deem these securities to be OTTI.


	December 31, 2017
	Less Than 12 Months				12 Months or Longer				Total
	Fair Value		Gross Unrealized Holding Losses		Fair Value		Gross Unrealized Holding Losses		Fair Value		Gross Unrealized Holding Losses
	(Dollars in thousands)
Investment securities available-for-sale:
Residential mortgage-backed securities	$	414,091	$	(1,828)	$	303,746	$	(6,274)	$	717,837	$	(8,102)
CMO/REMIC - residential		95,137		(487)		71,223		(1,595)		166,360		(2,082)
Municipal bonds		946		(4)		13,956		(240)		14,902		(244)

Total available-for-sale securities	$	510,174	$	(2,319)	$	388,925	$	(8,109)	$	899,099	$	(10,428)

Investment securities held-to-maturity:
Government agency/GSE	$	18,950	$	(27)	$	43,495	$	(2,107)	$	62,445	$	(2,134)
Residential mortgage-backed securities		51,297		(188)		55,306		(194)		106,603		(382)
CMO		-		-		216,431		(8,641)		216,431		(8,641)
Municipal bonds		32,069		(492)		66,217		(3,298)		98,286		(3,790)

Total held-to-maturity securities	$	102,316	$	(707)	$	381,449	$	(14,240)	$	483,765	$	(14,947)


	December 31, 2016
	Less Than 12 Months				12 Months or Longer				Total
	Fair Value		Gross Unrealized Holding Losses		Fair Value		Gross Unrealized Holding Losses		Fair Value		Gross Unrealized Holding Losses
	(Dollars in thousands)
Investment securities available-for-sale:
Residential mortgage-backed securities	$	583,143	$	(6,232)	$	-	$	-	$	583,143	$	(6,232)
CMO/REMIC - residential		128,595		(1,485)		-		-		128,595		(1,485)
Municipal bonds		23,255		(954)		5,981		(1)		29,236		(955)

Total available-for-sale securities	$	734,993	$	(8,671)	$	5,981	$	(1)	$	740,974	$	(8,672)

Investment securities held-to-maturity:
Government agency/GSE	$	76,854	$	(1,972)	$	-	$	-	$	76,854	$	(1,972)
Residential mortgage-backed securities		191,807		(1,892)		-		-		191,807		(1,892)
CMO		237,611		(6,808)		-		-		237,611		(6,808)
Municipal bonds		145,804		(3,711)		36,971		(1,057)		182,775		(4,768)

Total held-to-maturity securities	$	652,076	$	(14,383)	$	36,971	$	(1,057)	$	689,047	$	(15,440)

The following summarizes our analysis of these securities and the unrealized losses. This assessment was based on the following factors: i) the length of the time and the extent to which the fair value has been less than amortized cost; ii) adverse condition specifically related to the security, an industry, or a geographic area and whether or not the Company expects to recover the entire amortized cost, iii) historical and implied volatility of the fair value of the security; iv) the payment structure of the security and the likelihood of the issuer being able to make payments in the future; v) failure of the issuer of the security to make scheduled interest or principal payments, vi) any changes to the rating of the security by a rating agency, and vii) recoveries or additional declines in fair value subsequent to the balance sheet date.

Government Agency & Government-Sponsored Enterprise (“GSE”) — The government agency bonds are backed by the full faith and credit of agencies of the U.S. Government. While the Government-Sponsored Enterprise bonds are not expressly guaranteed by the U.S. Government, they are currently being supported by the U.S. Government under a conservatorship arrangement. As of December 31, 2017, approximately $101.3 million in U.S. government agency bonds were callable. These securities are bullet securities, that is, they have a defined maturity date on which the principal is paid. The contractual term of these investments provides that the Company will receive the face value of the bond at maturity which will equal the amortized cost of the bond. Interest is received throughout the life of the security. Accordingly, it is expected that the securities would not be settled at a price less than the amortized cost of the bonds.

Mortgage-Backed Securities (“MBS”) and CMO/REMIC — Most of the Company’s mortgage-backed and CMO/REMIC securities are issued by Government Agencies or Government-Sponsored Enterprises such as Ginnie Mae, Fannie Mae and Freddie Mac. These securities are collateralized or backed by the underlying residential or commercial mortgages. All mortgage-backed securities are considered to be rated investment grade with a weighted average life of approximately 4.0 years. Of the total MBS/CMO, 100.00% have the implied guarantee of U.S. Government-Sponsored Agencies and Enterprises. Accordingly, it is expected that the securities would not be settled at a price less than the amortized cost of the bonds. There were no credit-related OTTI recognized in earnings for the years ended December 31, 2017 and 2016.

Municipal Bonds — The majority of the Company’s municipal bonds, with maturities of approximately 9.9 years, are insured by the largest U.S. bond insurance companies. The Company diversifies its holdings by owning selections of securities from different issuers and by holding securities from geographically diversified municipal issuers, thus reducing the Company’s exposure to any single adverse event. The decline in fair value is primarily due to the changes in interest rates. Since the Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized costs, these investments are not considered OTTI at December 31, 2017.

At December 31, 2017 and 2016, investment securities having a carrying value of approximately $1.91 billion and $2.19 billion, respectively, were pledged to secure public deposits, short and long-term borrowings, and for other purposes as required or permitted by law.

The amortized cost and fair value of debt securities at December 31, 2017, by contractual maturity, are shown in the table below. Although mortgage-backed securities and CMO/REMIC have contractual maturities through 2057, expected maturities will differ from contractual maturities because borrowers may have the right to prepay such obligations without penalty. Mortgage-backed and CMO/REMIC securities are included in maturity categories based upon estimated average lives which incorporate estimated prepayment speeds.


	December 31, 2017
	Available-for-sale				Held-to-maturity
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
Due in one year or less	$	17,864	$	18,089	$	885	$	882
Due after one year through five years		1,929,815		1,932,602		175,899		173,251
Due after five years through ten years		96,678		96,200		271,579		268,426
Due after ten years		33,774		34,094		381,527		376,656

Total investment securities	$	2,078,131	$	2,080,985	$	829,890	$	819,215

The investment in FHLB stock is periodically evaluated for impairment based on, among other things, the capital adequacy of the FHLB and its overall financial condition. No impairment losses have been recorded through December 31, 2017.