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 September 30, 2020 and December 31, 2019 (in thousands):

	September 30, 2020
	Amortized Cost		Gross Unrealized Gains ⁽¹⁾		Gross Unrealized Losses ⁽¹⁾			Estimated Fair Value
Available-for-sale securities
U.S. government agency securities	$	4,540	$	90	$	—		$	4,630
State and municipal securities		2,401		58		—			2,459
Mortgage-backed securities:
Agency		664,899		17,491		(216	)		682,174
Commercial		93,864		3,957		—			97,821
Non-agency		6,793		70		(84	)		6,779
Corporate fixed income securities		581,249		24,349		(43	)		605,555
Asset-backed securities		1,438,951		3,502		(17,613	)		1,424,840
	$	2,792,697	$	49,517	$	(17,956	)	$	2,824,258
Held-to-maturity securities ⁽²⁾
Asset-backed securities	$	3,397,713	$	3,415	$	(66,095	)	$	3,335,033

	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 September 30, 2020, we did not have an allowance for credit losses recorded on our investment portfolio.

Accrued interest receivable for our investment portfolio at September 30, 2020 was $25.1 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.

There were no sales of available-for-sale securities during the three months ended September 30, 2020. For the nine months ended September 30, 2020, we received proceeds of $491.9 million, from the sale of available-for-sale securities, which resulted in a realized loss of $0.5 million. For the three and nine months ended September 30, 2019, we received proceeds of $486.5 million and $641.8 million, respectively, from the sale of available-for-sale securities, which resulted in an immaterial realized gain for the third quarter of 2019 and a realized loss of $0.3 million for the nine months ended September 30, 2019.

During the second quarter of 2020, the Company transferred $313.0 million of certain asset-backed securities from the available-for-sale category to held-to-maturity. Management determined that it has both the positive intent and ability to hold these securities to maturity. The reclassification of these securities was accounted for at fair value. On the date of transfer, the difference between the par value and the fair value of these securities resulted in a premium or discount that, under amortized cost accounting, will be amortized as a yield adjustment to interest income using the interest method. There were no gains or losses recognized as a result of this transfer.

During the third quarter of 2019, the Company transferred certain mortgage-backed securities from the held-to-maturity category to available-for sale. As of August 1, 2019, the securities reclassified had a fair value of $1.1 billion and resulted in a net of tax increase to other comprehensive income of $17.9 million for the three and nine months ended September 30, 2019.

During the three months ended September 30, 2020 and September 30, 2019, unrealized gains, net of deferred taxes, of $19.1 million and unrealized losses, net of deferred taxes, of $1.6 million were recorded in accumulated other comprehensive loss in the consolidated statements of financial condition. During the nine months ended September 30, 2020 and September 30, 2019, unrealized gains, net of deferred taxes, of $22.5 million and unrealized gains, net of deferred taxes, of $40.5 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 September 30, 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.

	September 30, 2020				December 31, 2019
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Available-for-sale securities
Within one year	$	152,731	$	154,255	$	6,861	$	6,871
After one year through three years		85,773		88,263		229,184		229,760
After three years through five years		302,285		320,037		422,236		429,909
After five years through ten years		528,866		527,815		409,664		411,680
After ten years		1,723,042		1,733,888		2,186,096		2,176,517
	$	2,792,697	$	2,824,258	$	3,254,041	$	3,254,737
Held-to-maturity securities
After three years through five years	$	6,537	$	6,533	$	—	$	—
After five years through ten years		1,302,344		1,281,809		598,250		597,166
After ten years		2,088,832		2,046,691		2,257,969		2,230,717
	$	3,397,713	$	3,335,033	$	2,856,219	$	2,827,883

The maturities of our available-for-sale (fair value) and held-to-maturity (amortized cost) securities at September 30, 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	$	2,318	$	2,312	$	—	$	—	$	4,630
State and municipal securities		—		—		2,459		—		2,459
Mortgage-backed securities:
Agency		11		444		24,017		657,702		682,174
Commercial		18,656		22		—		79,143		97,821
Non-agency		6,066		—		—		713		6,779
Corporate fixed income securities		127,204		405,522		55,732		17,097		605,555
Asset-backed securities		—		—		445,607		979,233		1,424,840
	$	154,255	$	408,300	$	527,815	$	1,733,888	$	2,824,258
Held-to-maturity securities
Asset-backed securities	$	—	$	6,537	$	1,302,344	$	2,088,832	$	3,397,713

At September 30, 2020 and December 31, 2019, securities of $188.4 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 September 30, 2020 and December 31, 2019, securities of $1.5 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 September 30, 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
Mortgage-backed securities:
Agency	$	(118	)	$	6,797	$	(98	)	$	10,191	$	(216	)	$	16,988
Non-agency		—			—		(84	)		713		(84	)		713
Corporate fixed income securities		(43	)		13,956		—			—		(43	)		13,956
Asset-backed securities		(8,016	)		668,379		(9,597	)		622,139		(17,613	)		1,290,518
	$	(8,177	)	$	689,132	$	(9,779	)	$	633,043	$	(17,956	)	$	1,322,175

At September 30, 2020, the amortized cost of 91 securities classified as available for sale exceeded their fair value by $18.0 million, of which $9.8 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 September 30, 2020, was $1.3 billion, which was 46.8% 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 September 30, 2020 (in thousands):

	AAA		AA		A		C		Total
Held-to-maturity securities
Asset-backed securities	$	423,043	$	2,956,572	$	15,500	$	2,598	$	3,397,713