The amortized cost and estimated fair value of investment securities are summarized below. The majority of securities held are

available-for-sale

securities with fair value based on quoted prices for similar assets in active markets or quoted prices for identical assets in markets that are not active. Estimated fair values were obtained from an independent pricing service based upon market quotes.


	December 31, 2020
	Amortized Cost		Gross Unrealized Holding Gain		Gross Unrealized Holding Loss			Fair Value		Total Percent
	(Dollars in thousands)
Investment securities available-for-sale:
Mortgage-backed securities	$	1,857,030	$	48,006	$	(101	)	$	1,904,935		79.41	%
CMO/REMIC		457,548		5,515		(249	)		462,814		19.29	%
Municipal bonds		28,707		1,578		-			30,285		1.26	%
Other securities		889		-		-			889		0.04	%

Total available-for-sale securities	$	2,344,174	$	55,099	$	(350	)	$	2,398,923		100.00	%

Investment securities held-to-maturity:
Government agency/GSE	$	98,663	$	5,877	$	-		$	104,540		17.05	%
Mortgage-backed securities		146,382		7,644		(32	)		153,994		25.30	%
CMO/REMIC		145,309		5,202		-			150,511		25.11	%
Municipal bonds		188,272		6,980		(74	)		195,178		32.54	%

Total held-to-maturity securities	$	578,626	$	25,703	$	(106	)	$	604,223		100.00	%


	December 31, 2019
	Amortized Cost		Gross Unrealized Holding Gain		Gross Unrealized Holding Loss			Fair Value		Total Percent
	(Dollars in thousands)
Investment securities available-for-sale:
Mortgage-backed securities	$	1,185,757	$	21,306	$	(750	)	$	1,206,313		69.32	%
CMO/REMIC		493,214		1,392		(896	)		493,710		28.37	%
Municipal bonds		38,506		850		(2	)		39,354		2.26	%
Other securities		880		-		-			880		0.05	%

Total available-for-sale securities	$	1,718,357	$	23,548	$	(1,648	)	$	1,740,257		100.00	%

Investment securities held-to-maturity:
Government agency/GSE	$	117,366	$	2,280	$	(657	)	$	118,989		17.40	%
Mortgage-backed securities		168,479		2,083		(54	)		170,508		24.98	%
CMO/REMIC		192,548		-		(2,458	)		190,090		28.55	%
Municipal bonds		196,059		3,867		(565	)		199,361		29.07	%

Total held-to-maturity securities	$	674,452	$	8,230	$	(3,734	)	$	678,948		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.


	Year Ended December 31,
	2020		2019		2018
	(Dollars in thousands)
Investment securities available-for-sale:
Taxable	$	35,129	$	38,189	$	44,423
Tax-advantaged		923		1,141		1,565

Total interest income from available-for-sale securities		36,052		39,330		45,988

Investment securities held-to-maturity:
Taxable		9,542		11,498		11,848
Tax-advantaged		4,681		5,890		7,053

Total interest income from held-to-maturity securities		14,223		17,388		18,901

Total interest income from investment securities	$	50,275	$	56,718	$	64,889

The adoption of CECL did not have a material impact on the accounting for investment securities, as approximately 93% of the total investment securities portfolio at December 31, 2020 represents securities issued by the U.S. government or U.S. government-sponsored enterprises, with the implied guarantee of payment of principal and interest. The remaining securities are predominately

AA-

or better general-obligation municipal bonds. The allowance for credit losses for

held-to-maturity

investment securities under the new CECL model was zero at December 31, 2020.

We adopted ASU

2016-13

on January 1, 2020, on a prospective basis. Under this ASU, once it is determined that a credit loss has occurred, an allowance for credit losses is established on our AFS and HTM securities. Prior to adoption of this standard, when a decline in fair value of a debt security was determined to be other than temporary, an impairment charge for the credit component was recorded, and a new cost basis in the investment was established. Management determined that there were no credit losses for securities in an unrealized loss position for 2020.

The following table presents the Company’s

available-for-sale

investment securities, by investment category, in an unrealized loss position for which an allowance for credit losses has not been recorded as of December 31, 2020.


	December 31, 2020
	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:
Mortgage-backed securities	$	72,219	$	(101	)	$	-	$	-	$	72,219	$	(101	)
CMO/REMIC		96,974		(249	)		-		-		96,974		(249	)
Municipal bonds		-		-			-		-		-		-

Total available-for-sale securities	$	169,193	$	(350	)	$	-	$	-	$	169,193	$	(350	)

The table below presents 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, 2019, prior to adoption of ASU

2016-13.

Management previously 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 interest 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 other-than-temporarily-impaired.



	December 31, 2019
	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:
Mortgage-backed securities	$	20,289	$	(6	)	$	97,964	$	(744	)	$	118,253	$	(750	)
CMO/REMIC		177,517		(705	)		34,565		(191	)		212,082		(896	)
Municipal bonds		-		-			563		(2	)		563		(2	)

Total available-for-sale securities	$	197,806	$	(711	)	$	133,092	$	(937	)	$	330,898	$	(1,648	)

Investment securities held-to-maturity:
Government agency/GSE	$	28,359	$	(252	)	$	19,405	$	(405	)	$	47,764	$	(657	)
Mortgage-backed securities		10,411		(54	)		-		-			10,411		(54	)
CMO/REMIC		23,897		(104	)		166,193		(2,354	)		190,090		(2,458	)
Municipal bonds		7,583		(32	)		29,981		(533	)		37,564		(565	)

Total held-to-maturity securities	$	70,250	$	(442	)	$	215,579	$	(3,292	)	$	285,829	$	(3,734	)

The following summarizes our analysis of these securities and the unrealized losses.

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. 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 2.6 years. Of the total MBS/CMO, 100% 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 impairments for the year ended December 31, 2020 and no OTTI recognized in earnings for the year ended December 31, 2019.

Municipal Bonds — The majority of the Company’s municipal bonds, with maturities of approximately 10.2 years, represented approximately 7% of the total investment portfolio and are predominately AA or higher rated securities. 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 were not considered impaired at December 31, 2020 and there were no losses recognized in earnings for the year ended December 31, 2019.

At December 31, 2020 and 2019, investment securities having a carrying value of approximately $1.81 billion and $1.64 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, 2020, by contractual maturity, are shown in the table below. Although mortgage-backed and CMO/REMIC securities have weighted average remaining contractual maturities of approximately 18 years, 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, 2020
	Available-for-sale				Held-to-maturity
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
Due in one year or less	$	10,473	$	10,499	$	2,724	$	2,751
Due after one year through five years		2,204,046		2,255,300		305,248		317,994
Due after five years through ten years		92,729		94,795		75,561		79,295
Due after ten years		36,926		38,329		195,093		204,183

Total investment securities	$	2,344,174	$	2,398,923	$	578,626	$	604,223

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, 2020