The following tables provide a summary of the amortized cost and fair values of the available-for-sale securities and held-to-maturity securities at March 31, 2020 and December 31, 2019 (in thousands):

	March 31, 2020
	Amortized Cost		Gross Unrealized Gains ⁽¹⁾		Gross Unrealized Losses ⁽¹⁾			Estimated Fair Value
Available-for-sale securities
U.S. government agency securities	$	5,534	$	116	$	—		$	5,650
State and municipal securities		17,079		63		—			17,142
Mortgage-backed securities:
Agency		807,043		22,545		(155	)		829,433
Commercial		108,144		524		(482	)		108,186
Non-agency		8,620		118		(94	)		8,644
Corporate fixed income securities		741,219		3,460		(17,089	)		727,590
Asset-backed securities		1,776,630		836		(108,021	)		1,669,445
	$	3,464,269	$	27,662	$	(125,841	)	$	3,366,090
Held-to-maturity securities ⁽²⁾
Asset-backed securities	$	3,085,824	$	1,458	$	(389,452	)	$	2,697,830

	December 31, 2019
	Amortized Cost		Gross Unrealized Gains ⁽¹⁾		Gross Unrealized Losses ⁽¹⁾			Estimated Fair Value
Available-for-sale securities
U.S. government agency securities	$	5,028	$	39	$	—		$	5,067
State and municipal securities		24,198		99		—			24,297
Mortgage-backed securities:
Agency		840,659		3,070		(5,851	)		837,878
Commercial		109,982		269		(714	)		109,537
Non-agency		9,731		50		(23	)		9,758
Corporate fixed income securities		664,028		11,283		—			675,311
Asset-backed securities		1,600,415		679		(8,205	)		1,592,889
	$	3,254,041	$	15,489	$	(14,793	)	$	3,254,737
Held-to-maturity securities ⁽²⁾
Asset-backed securities	$	2,856,219	$	5,960	$	(34,296	)	$	2,827,883

Effective January 1, 2020, we adopted the new accounting standard for credit losses that requires evaluation of available-for-sale and held-to-maturity debt securities for any expected losses with recognition of an allowance for credit losses, when applicable. For more information, see Note 1 – Nature of Operations, Basis of Presentation, and Summary of Significant Accounting Policies. At March 31, 2020, we did not have an allowance for credit losses recorded on our investment portfolio.

Accrued interest receivable for our investment portfolio at March 31, 2020 was $38.2 million and is reported in other assets in the consolidated statements of financial condition. We do not include reserves for interest receivable in the measurement of the allowance for credit losses.

During the three months ended March 31, 2020, we received proceeds of $288.3 million, from the sale of available-for-sale securities, which resulted in a realized loss of $0.7 million. There were no sales of available-for-sale securities during the three months ended March 31, 2019.

During the three months ended March 31, 2020 and March 31, 2019, unrealized losses, net of deferred taxes, of $73.2 million and unrealized gains, net of deferred taxes of $25.8 million were recorded in accumulated other comprehensive loss in the consolidated statements of financial condition.

The table below summarizes the amortized cost and fair values of our securities by contractual maturity at March 31, 2020 and December 31, 2019 (in thousands). Expected maturities may differ significantly from contractual maturities, as issuers may have the right to call or prepay obligations with or without call or prepayment penalties.

	March 31, 2020				December 31, 2019
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Available-for-sale securities
Within one year	$	26,838	$	26,980	$	6,861	$	6,871
After one year through three years		261,013		259,331		229,184		229,760
After three years through five years		422,686		412,819		422,236		429,909
After five years through ten years		478,472		453,334		409,664		411,680
After ten years		2,275,260		2,213,626		2,186,096		2,176,517
	$	3,464,269	$	3,366,090	$	3,254,041	$	3,254,737
Held-to-maturity securities
After five years through ten years	$	686,300	$	618,937	$	598,250	$	597,166
After ten years		2,399,524		2,078,893		2,257,969		2,230,717
	$	3,085,824	$	2,697,830	$	2,856,219	$	2,827,883

The maturities of our available-for-sale (fair value) and held-to-maturity (amortized cost) securities at March 31, 2020, are as follows (in thousands):

	Within 1 Year		1-5 Years		5-10 Years		After 10 Years		Total
Available-for-sale securities ⁽¹⁾
U.S. government agency securities	$	1,761	$	3,889	$	—	$	—	$	5,650
State and municipal securities		—		—		2,463		14,679		17,142
Mortgage-backed securities:
Agency		33		676		786		827,938		829,433
Commercial		—		31,607		—		76,579		108,186
Non-agency		—		7,827		—		817		8,644
Corporate fixed income securities		25,186		628,151		74,253		—		727,590
Asset-backed securities		—		—		375,832		1,293,613		1,669,445
	$	26,980	$	672,150	$	453,334	$	2,213,626	$	3,366,090
Held-to-maturity securities
Asset-backed securities	$	—	$	—	$	686,300	$	2,399,524	$	3,085,824

At March 31, 2020 and December 31, 2019, securities of $526.7 million and $801.5 million, respectively, were pledged at the Federal Home Loan Bank as collateral for borrowings and letters of credit obtained to secure public deposits. At March 31, 2020 and December 31, 2019, securities of $1.3 billion and $816.1 million, respectively, were pledged with the Federal Reserve discount window.

The following table shows the gross unrealized losses and fair value of the Company’s investment securities with unrealized losses, aggregated by investment category and length of time the individual investment securities have been in continuous unrealized loss positions, at March 31, 2020 (in thousands):

	Less than 12 months					12 months or more					Total
	Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value
Available-for-sale securities
Agency	$	(122	)	$	23,806	$	(33	)	$	10,315	$	(155	)	$	34,121
Commercial		(482	)		61,706		—			—		(482	)		61,706
Non-agency		—			—		(94	)		817		(94	)		817
Corporate fixed income securities		(17,089	)		492,713		—			—		(17,089	)		492,713
Asset-backed securities		(67,624	)		1,096,278		(40,397	)		466,319		(108,021	)		1,562,597
	$	(85,317	)	$	1,674,503	$	(40,524	)	$	477,451	$	(125,841	)	$	2,151,954

At March 31, 2020, the amortized cost of 165 securities classified as available for sale exceeded their fair value by $125.8 million, of which $40.5 million related to investment securities that had been in a loss position for 12 months or longer. The total fair value of these investments at March 31, 2020, was $2.2 billion, which was 63.9% of our available-for-sale portfolio.

The Company uses Moody credit ratings as the credit quality indicator for its held-to-maturity debt securities. Each security is evaluated at least quarterly. The indicators represent the rating for debt securities, as of the date presented, based on the most recent assessment performed. The following table shows the amortized cost of our held-to-maturity securities by credit quality indicator at March 31, 2020 (in thousands):

	AAA		AA		A		C		Total
Held-to-maturity securities
Asset-backed securities	$	109,335	$	2,958,230	$	15,500	$	2,759	$	3,085,824