
	At December 31, 2020
(In thousands)	Amortized Cost (1)		Unrealized Gains		Unrealized Losses		Fair Value		Allowance (2)		Net Carrying Value
Agency CMO	$	91,622	$	1,785	$	(241)	$	93,166	$	—	$	91,622
Agency MBS	2,419,751		137,863		(84)		2,557,530		—		2,419,751
Agency CMBS	2,101,227		60,484		(2,213)		2,159,498		—		2,101,227
Municipal bonds and notes	739,507		60,371		(3)		799,875		299		739,208
CMBS	216,081		9,214		—		225,295		—		216,081
Held-to-maturity securities	$	5,568,188	$	269,717	$	(2,541)	$	5,835,364	$	299	$	5,567,889

	At December 31, 2019
(In thousands)	Amortized Cost (1)		Unrealized Gains		Unrealized Losses		Fair Value		Allowance (2)		Net Carrying Value
Agency CMO	$	167,443	$	1,123	$	(1,200)	$	167,366	$	—	$	167,443
Agency MBS	2,957,900		60,602		(8,733)		3,009,769		—		2,957,900
Agency CMBS	1,172,491		6,444		(5,615)		1,173,320		—		1,172,491
Municipal bonds and notes	740,431		32,709		(21)		773,119		—		740,431
CMBS	255,653		2,278		(852)		257,079		—		255,653
Held-to-maturity securities	$	5,293,918	$	103,156	$	(16,421)	$	5,380,653	$	—	$	5,293,918

(1)Amortized cost excludes accrued interest receivable of $22.1 million and $21.8 million at December 31, 2020 and December 31, 2019, respectively, which is included in accrued interest and other assets in the accompanying Consolidated Balance Sheets.

(2)The Company adopted the new accounting standard for credit losses on January 1, 2020. For periods subsequent to adoption, the allowance is calculated under the CECL methodology and the resulting provision includes expected credit losses on held-to-maturity securities. The prior period did not have an allowance under applicable GAAP for that period.

Agency securities represent obligations issued by a U.S. government-sponsored enterprise or other federally-related entity and are either explicitly or implicitly guaranteed and therefore, assumed to be zero loss. Securities with unrealized losses and no allowance are considered to be of high credit quality, and therefore, no credit loss as of December 31, 2020. The current unrealized loss position of certain agency securities with no credit loss allowance can be attributed to the changing interest rate environment. An allowance for credit losses on investment securities held-to-maturity of $397 thousand was recorded for certain Municipal bonds and notes to account for expected lifetime credit loss upon adoption of the new accounting standard for credit losses. Expected lifetime credit loss on investment securities held-to-maturity is primarily attributed to securities not rated.

The Company monitors the credit quality of held-to-maturity debt securities through credit ratings by Standard & Poor's Rating Services (S&P), Moody's Investor Services (Moody's), Fitch Ratings, Inc., Kroll Bond Rating Agency, or DBRS Inc. Credit ratings express opinions about the credit quality of a security. Investment grade securities are rated BBB- or higher by S&P, or Baa3 or higher by Moody's, and generally considered by the rating agencies and market participants to be of low credit risk. Conversely, securities rated below investment grade, labeled as speculative grade by the rating agencies, are considered to have distinctively higher credit risk than investment grade securities. Securities shown below that are not rated are collateralized with U.S. Treasury obligations, and credit quality indicators are updated at each quarter end.


	Investment Grade
(In thousands)	Aaa		Aa1		Aa2		Aa3		A1		A2		A3		Baa2		Not Rated
Agency CMOs	$	—	$	91,622	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Agency MBS	—		2,419,751		—		—		—		—		—		—		—
Agency CMBS	—		2,101,227		—		—		—		—		—		—		—
Municipal bonds and notes	209,376		165,056		201,081		115,619		33,264		8,475		2,066		190		4,380
CMBS	216,081		—		—		—		—		—		—		—		—
Total held-to-maturity	$	425,457	$	4,777,656	$	201,081	$	115,619	$	33,264	$	8,475	$	2,066	$	190	$	4,380


	At December 31, 2020
(In thousands)	Amortized Cost		Fair Value
Due in one year or less	$	680	$	685
Due after one year through five years	4,458		4,711
Due after five through ten years	278,974		294,528
Due after ten years	5,284,076		5,535,440
Total held-to-maturity debt securities	$	5,568,188	$	5,835,364

For the maturity schedule above, investment securities which are not due at a single maturity date have been categorized based on the maturity date of the underlying collateral. Actual principal cash flows may differ from this maturity date presentation as borrowers have the right to repay obligations with or without prepayment penalties.


	At December 31, 2020
(In thousands)	Amortized Cost (1)		Unrealized Gains		Unrealized Losses		Fair Value (2)
Agency CMO	$	148,711	$	6,000	$	(98)	$	154,613
Agency MBS	1,389,100		68,598		(289)		1,457,409
Agency CMBS	1,092,430		26,317		(1,514)		1,117,233
CMBS	512,759		1,082		(5,823)		508,018
CLO	76,693		—		(310)		76,383
Corporate debt	14,557		—		(1,437)		13,120
Available-for-sale securities	$	3,234,250	$	101,997	$	(9,471)	$	3,326,776

	At December 31, 2019
	Amortized Cost (1)		Unrealized Gains		Unrealized Losses		Fair Value (2)
Agency CMO	$	184,500	$	2,218	$	(917)	$	185,801
Agency MBS	1,580,743		35,456		(4,035)		1,612,164
Agency CMBS	587,974		513		(6,935)		581,552
CMBS	432,085		38		(252)		431,871
CLO	92,628		45		(468)		92,205
Corporate debt	23,485		—		(1,245)		22,240
Available-for-sale securities	$	2,901,415	$	38,270	$	(13,852)	$	2,925,833

(1)Amortized cost excludes accrued interest receivable of $7.5 million and $8.1 million at December 31, 2020 and December 31, 2019, respectively, which is included in accrued interest and other assets in the accompanying Consolidated Balance Sheets.

The following tables provide information on fair value and unrealized losses for the individual available-for-sale securities with an unrealized loss, for which an allowance for credit losses on investment securities available-for-sale has not been recorded, aggregated by classification and length of time that the individual investment securities have been in a continuous unrealized loss position:


	At December 31, 2020
	Less Than Twelve Months				Twelve Months or Longer				Total
(Dollars in thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		# of Holdings	Fair Value		Unrealized Losses
Agency CMO	$	13,137	$	(49)	$	5,944	$	(49)	5	$	19,081	$	(98)
Agency MBS	33,742		(219)		4,561		(70)		30	38,303		(289)
Agency CMBS	376,330		(1,514)		—		—		8	376,330		(1,514)
CMBS	409,591		(5,486)		23,167		(337)		38	432,758		(5,823)
CLO	57,728		(265)		18,655		(45)		4	76,383		(310)
Corporate debt	4,100		(166)		9,020		(1,271)		3	13,120		(1,437)
Available-for-sale in unrealized loss position	$	894,628	$	(7,699)	$	61,347	$	(1,772)	88	$	955,975	$	(9,471)


	At December 31, 2019
	Less Than Twelve Months				Twelve Months or Longer				Total
(Dollars in thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		# of Holdings	Fair Value		Unrealized Losses
Agency CMO	$	36,447	$	(352)	$	32,288	$	(565)	9	$	68,735	$	(917)
Agency MBS	41,408		(193)		299,674		(3,842)		79	341,082		(4,035)
Agency CMBS	174,406		(1,137)		357,717		(5,798)		34	532,123		(6,935)
CMBS	355,260		(232)		7,480		(20)		29	362,740		(252)
CLO	—		—		43,232		(468)		2	43,232		(468)
Corporate debt	—		—		22,240		(1,245)		4	22,240		(1,245)
Available-for-sale in unrealized loss position	$	607,521	$	(1,914)	$	762,631	$	(11,938)	157	$	1,370,152	$	(13,852)

Unrealized losses on available-for-sale debt securities presented in the previous table have not been recognized in the accompanying Consolidated Statements of Income because the securities are high credit quality, investment grade securities that the Company does not intend to sell and will not be required to sell prior to their anticipated recovery, and the decline in fair value is primarily attributable to wider spreads in selected asset classes. Fair value is expected to recover as the securities approach maturity. As of December 31, 2020, none of the available-for-sale investment securities were in non-accrual status.


	At December 31, 2020
(In thousands)	Amortized Cost		Fair Value
Due in one year or less	$	—	$	—
Due after one year through five years	1,448		1,489
Due after five through ten years	252,601		248,958
Due after ten years	2,980,201		3,076,329
Total available-for-sale debt securities	$	3,234,250	$	3,326,776

For the maturity schedule above, investment securities which are not due at a single maturity date, have been categorized based on the maturity date of the underlying collateral. Actual principal cash flows may differ from this maturity date presentation as borrowers have the right to prepay obligations with or without prepayment penalties.


	Years ended December 31,
(In thousands)	2020		2019		2018
Proceeds from sales	$	8,963	$	70,087	$	—

Gross realized gains on sales	$	8	$	773	$	—
Gross realized losses on sales	—		744		—
Gain on sale of investment securities, net	$	8	$	29	$	—

At December 31, 2020, the Company had a carrying value of $1.3 billion in callable debt securities in its CMBS, CLO, and municipal bond portfolios. The Company considers this prepayment risk in the evaluation of its interest rate risk profile.

Investment securities with a carrying value totaling $3.9 billion at December 31, 2020 and $2.7 billion at December 31, 2019 were pledged to secure public funds, trust deposits, repurchase agreements, and for other purposes, as required or permitted by law.