The following tables summarize the amortized cost and fair values of securities available-for-sale and securities held-to-maturity as of the dates shown and the corresponding amounts of gross unrealized gains and losses:

March 31, 2021	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Available-for-sale
U.S. Treasury Notes	$	13,475	$	243	$	—		$	13,718
U.S. Government agencies		142,134		721		(3,270	)		139,585
Obligations of states, municipalities, and political subdivisions		102,966		3,854		(292	)		106,528
Residential mortgage-backed securities
Agency		985,375		4,802		(19,085	)		971,092
Non-agency		68,562		149		(761	)		67,950
Commercial mortgage-backed securities
Agency		269,997		4,009		(4,795	)		269,211
Corporate securities		61,018		1,602		(68	)		62,552
Asset-backed securities		45,188		83		—			45,271
Total	$	1,688,715	$	15,463	$	(28,271	)	$	1,675,907

December 31, 2020	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Available-for-sale
U.S. Treasury Notes	$	23,468	$	344	$	—		$	23,812
U.S. Government agencies		113,088		600		(137	)		113,551
Obligations of states, municipalities, and political subdivisions		135,513		6,991		(85	)		142,419
Residential mortgage-backed securities
Agency		764,951		13,645		(205	)		778,391
Non-agency		32,654		332		(5	)		32,981
Commercial mortgage-backed securities
Agency		244,496		6,046		(390	)		250,152
Corporate securities		59,020		1,850		(102	)		60,768
Asset-backed securities		45,255		26		(125	)		45,156
Total	$	1,418,445	$	29,834	$	(1,049	)	$	1,447,230

December 31, 2020	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Held-to-maturity
Obligations of states, municipalities, and political subdivisions	$	4,395	$	178	$	—	$	4,573
Total	$	4,395	$	178	$	—	$	4,573

The Company did not classify securities as trading during the three months ended March 31, 2021 or during 2020.

Gross unrealized losses and fair values, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of March 31, 2021 and December 31, 2020, are summarized as follows:

			Less than 12 Months					12 Months or Longer					Total
March 31, 2021	# of Securities		Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Available-for-sale
U.S. Government agencies		13	$	106,908	$	(3,270	)	$	—	$	—		$	106,908	$	(3,270	)
Obligations of states, municipalities and political subdivisions		8		13,689		(292	)		—		—			13,689		(292	)
Residential mortgage-backed securities
Agency		59		781,666		(19,074	)		439		(11	)		782,105		(19,085	)
Non-agency		4		28,484		(761	)		—		—			28,484		(761	)
Commercial mortgage-backed securities
Agency		20		106,172		(4,795	)		—		—			106,172		(4,795	)
Corporate securities		4		8,470		(68	)		—		—			8,470		(68	)
Total		108	$	1,045,389	$	(28,260	)	$	439	$	(11	)	$	1,045,828	$	(28,271	)

			Less than 12 Months					12 Months or Longer					Total
December 31, 2020	# of Securities		Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Available-for-sale
U.S. Government agencies		5	$	30,639	$	(137	)	$	—	$	—		$	30,639	$	(137	)
Obligations of states, municipalities and political subdivisions		2		210		(85	)		—		—			210		(85	)
Residential mortgage-backed securities
Agency		8		45,253		(198	)		472		(7	)		45,725		(205	)
Non-agency		2		3,963		(5	)		—		—			3,963		(5	)
Commercial mortgage-backed securities
Agency		8		55,554		(390	)		—		—			55,554		(390	)
Corporate securities		6		10,916		(102	)		—		—			10,916		(102	)
Asset-backed securities		6		24,436		(99	)		4,952		(26	)		29,388		(125	)
Total		37	$	170,971	$	(1,016	)	$	5,424	$	(33	)	$	176,395	$	(1,049	)

Certain securities have fair values less than amortized cost and, therefore, contain unrealized losses. The Company evaluated the securities that had an unrealized loss for other than temporary impairment and determined all declines in value to be temporary. There were 108 securities available-for-sale with unrealized losses at March 31, 2021. There were no securities held-to-maturity with unrealized losses at March 31, 2021. The Company anticipates full recovery of amortized cost with respect to these securities by maturity, or sooner, in the event of a more favorable market interest rate environment. The Company does not intend to sell these securities and it is not more likely than not that the Company will be required to sell them before recovery of their amortized cost basis, which may be at maturity.

The proceeds from all sales of securities available-for-sale, and the associated gains and losses, for the three months ended March 31, 2021 and 2020 are listed below:

There were $1.4 million in net gains reclassified from accumulated other comprehensive income into earnings for each of the three months ended March 31, 2021, and 2020, respectively.

Securities posted as collateral were $386.7 million and $731.8 million at March 31, 2021 and December 31, 2020, respectively, of which carrying amounts of $386.7 million and $323.9 million were pledged at March 31, 2021 and December 31, 2020, respectively. At March 31, 2021 and December 31, 2020, of those pledged, the carrying amounts of securities pledged as collateral for public fund deposits were $310.9 million and $245.1 million, respectively, and for customer repurchase agreements of $59.6 million and $64.1 million, respectively. At March 31, 2021 and December 31, 2020, there were no securities pledged for advances from the Federal Home Loan Bank. Other securities were pledged for derivative positions, letters of credit and for purposes required or permitted by law. At March 31, 2021 and December 31, 2020, there were no holdings of securities of any one issuer, other than the U.S. Government and its agencies, in an amount greater than 10% of stockholders’ equity.

At March 31, 2021, the amortized cost and fair value of debt securities are shown by contractual maturity. Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations with or without call or prepayment penalties. Securities not due at a single maturity date are shown separately.

	Amortized Cost		Fair Value
Available-for-sale
Due in one year or less	$	21,786	$	22,111
Due from one to five years		34,665		35,947
Due from five to ten years		212,875		213,519
Due after ten years		95,455		96,077
Mortgage-backed securities		1,323,934		1,308,253
Total	$	1,688,715	$	1,675,907
Held-to-maturity
Due from one to five years		3,892		4,066
Total	$	3,892	$	4,066