The following tables detail the amortized cost, allowance for credit losses and the estimated fair value of the Company's investments in available-for-sale and held-to-maturity debt securities. None of the Company's investments in debt securities are classified as trading.


	December 31, 2020
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Allowance for Credit Losses		Fair Value
Available-for-Sale Debt Securities
CMO	$	461,819	$	9,949	$	443	$	—	$	471,325
FNMA MBS	1,544,105		55,747		882		—		1,598,970
FHLMC MBS	190,856		12,142		105		—		202,893
GNMA MBS	22,716		1,046		—		—		23,762
GSE agency notes	230,769		1,987		649		—		232,107
	$	2,450,265	$	80,871	$	2,079	$	—	$	2,529,057
Held-to-Maturity Debt Securities(1)
State and political subdivisions	$	111,246	$	4,678	$	—	$	6	$	115,918
Foreign bonds	501		2		—		—		503
	$	111,747	$	4,680	$	—	$	6	$	116,421

(1)Held-to-maturity securities transferred from available-for-sale are included in held-to-maturity at amortized cost basis at the time of transfer. The amortized cost of transferred held-to-maturity securities included net unrealized gains of $0.4 million at December 31, 2020, which are offset in Accumulated other comprehensive income. At the time of transfer, there was no allowance for credit loss on the available-for-sale securities. Subsequent to transfer, the securities were evaluated for credit loss.


	December 31, 2019
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Available-for-Sale Debt Securities
CMO	$	336,194	$	4,578	$	542	$	340,230
FNMA MBS	1,219,522		25,717		2,786		1,242,453
FHLMC MBS	320,896		8,641		591		328,946
GNMA MBS	32,871		477		63		33,285
	$	1,909,483	$	39,413	$	3,982	$	1,944,914
Held-to-Maturity Debt Securities(1)
State and political subdivisions	$	131,600	$	3,023	$	—	$	134,623
Foreign bonds	2,001		1		—		2,002
	$	133,601	$	3,024	$	—	$	136,625

(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 transferred held-to-maturity securities included net unrealized gains of $0.6 million at December 31, 2019, which are offset in Accumulated other comprehensive income.


	Available-for-Sale
(Dollars in thousands)	Amortized Cost		Fair Value
December 31, 2020 (1)
Within one year	$	—	$	—
After one year but within five years	37,852		39,985
After five years but within ten years	239,845		251,874
After ten years	2,172,568		2,237,198
	$	2,450,265	$	2,529,057
December 31, 2019 (1)
Within one year	$	—	$	—
After one year but within five years	22,136		22,207
After five years but within ten years	194,197		194,376
After ten years	1,693,150		1,728,331
	$	1,909,483	$	1,944,914

	Held-to-Maturity
(Dollars in thousands)	Amortized Cost		Fair Value
December 31, 2020 (1)
Within one year	$	1,144	$	1,154
After one year but within five years	972		990
After five years but within ten years	35,967		37,317
After ten years	73,664		76,960
	$	111,747	$	116,421
December 31, 2019 (1)
Within one year	$	2,649	$	2,653
After one year but within five years	4,239		4,270
After five years but within ten years	35,288		35,967
After ten years	91,425		93,735
	$	133,601	$	136,625

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. The estimated weighted average duration of MBS was 2.7 years at December 31, 2020.

Investment securities with fair market values aggregating $1.3 billion and $1.1 billion were pledged as collateral for retail customer repurchase agreements, municipal deposits, and other obligations as of December 31, 2020 and 2019, respectively.

During the year ended December 31, 2020, the Company sold $305.8 million of debt securities categorized as available-for-sale, resulting in $9.1 million of realized gains and no realized losses. During the year ended December 31, 2019, the Company sold $618.2 million of debt securities categorized as available-for-sale, of which $578.8 million was related to the acquisition of Beneficial. The remaining $39.8 million resulted in realized gains of $0.3 million and no realized losses. During the year ended December 31, 2018, the Company sold $7.0 million of investment securities categorized as available-for-sale, resulting in realized gains of less than $0.1 million and no realized losses.

As of December 31, 2020, and December 31, 2019, the Company's debt securities portfolio had remaining unamortized premiums of $60.4 million and $15.1 million, respectively, and unaccreted discounts of $2.6 million and $4.1 million, respectively.

For debt securities in an unrealized loss position and an allowance has not been recorded, the table below shows the 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, 2020.


	Duration of Unrealized Loss Position
	Less than 12 months				12 months or longer				Total
(Dollars in thousands)	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Available-for-sale debt securities:
CMO	$	183,983	$	443	$	—	$	—	$	183,983	$	443
FNMA MBS	289,338		879		4,355		3		293,693		882
FHLMC MBS	5,191		105		—		—		5,191		105

GSE agency notes	101,016		649		—		—		101,016		649
	$	579,528	$	2,076	$	4,355	$	3	$	583,883	$	2,079

For debt securities in an unrealized loss position, the table below shows the Company's 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, 2019.


	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	$	47,376	$	481	$	7,999	$	61	$	55,375	$	542
FNMA MBS	310,312		2,681		6,522		105		316,834		2,786
FHLMC MBS	35,354		541		2,836		50		38,190		591
GNMA MBS	1,847		4		5,742		59		7,589		63
	$	394,889	$	3,707	$	23,099	$	275	$	417,988	$	3,982

Held-to-maturity debt securities:
State and political subdivisions(1)	$	523	$	—	$	—	$	—	$	523	$	—

At December 31, 2020, available-for-sale debt securities for which the amortized cost basis exceeded fair value totaled $583.9 million. Total unrealized losses on these securities were $2.1 million at December 31, 2020. The Company does not have the intent to sell, nor is it more likely than not it will be required to sell these securities before it is able to recover the amortized cost basis. The unrealized losses are the result of changes in market interest rates subsequent to purchase, not credit loss, as these are highly rated agency securities with no expected credit loss, in the event of a default. As a result, there is no allowance for credit losses recorded for available-for-sale debt securities as of December 31, 2020.

At December 31, 2020, held-to-maturity debt securities had an amortized cost basis of $111.7 million. The held-to-maturity debt security portfolio primarily consists of highly rated municipal bonds. The Company monitors credit quality of its debt securities through credit ratings.

As a result of the adoption of ASC 326 on January 1, 2020, the Company reviewed its held-to-maturity debt securities for potential credit losses. The following table presents the activity in the allowance for credit losses for debt securities held-to-maturity by major security type for the year ended December 31, 2020:


(Dollars in thousands)	State and political subdivisions		Foreign bonds
Allowance for credit losses:
Beginning balance	$	—	$	—
Impact of adoption ASC 326	8		—
Provision for credit losses	(2)		—

Charge-offs, net	—		—

Ending balance	$	6	$	—

Accrued interest receivable of $1.1 million as of December 31, 2020 for held-to-maturity debt securities was excluded from the evaluation of allowance for credit losses. There were no nonaccrual or past due held-to-maturity debt securities as of December 31, 2020.

The following tables detail the amortized cost, and the estimated fair value of the Company's equity investments, which are included in Other investments in the audited Consolidated Statements of Financial Condition.


	December 31, 2020
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Equity Investments
Visa Class B shares(1)	$	618	$	185	$	—	$	803
Other equity investments(2)	10,384		—		1,646		8,738
	$	11,002	$	185	$	1,646	$	9,541


	December 31, 2019
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Equity Investments
Visa Class B shares(1)	$	15,716	$	45,565	$	—	$	61,281
Other equity investments(2)	8,140		625		—		8,765
	$	23,856	$	46,190	$	—	$	70,046

(1)The Company recorded a net realized gain on sale of Visa Class B shares of $22.1 million and $3.8 million during the years ended December 31, 2020 and 2018, respectively. There were no such sales in 2019. These gains are recorded in Realized gain on sale of equity investment in the Consolidated Statements of Income. The Company recorded unrealized gains on its remaining investment in Visa Class B shares of $3.0 million, $25.6 million, and $20.7 million during the years ended December 31, 2020, 2019, and 2018, respectively, which is recorded in Unrealized gain on equity investment, net in the Consolidated Statements of Income.

(2)As of December 31, 2020 and 2019, the fair value balance of the investment in Spring EQ was $4.2 million and $3.4 million, respectively. The Company recorded an impairment loss of $2.3 million in the investment in Spring EQ during the first quarter of 2020, which is recorded in Unrealized gain on equity investment, net in the Consolidated Statements of Income. There were no impairment losses recorded on the Company's equity investments during the year ended December 31, 2019. During the second quarter of 2020, the Company amended its agreement with Spring EQ in an exchange for additional equity interest. The additional equity interest in Spring EQ was valued at $2.4 million.