Securities (Tables)

3 Months Ended

Mar. 31, 2021

Investments Debt And Equity Securities [Abstract]

Summary of Amortized Cost and Fair Values of Securities Available-for-sale, and Held to Maturity

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

March 31, 2021	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Held-to-maturity
Obligations of states, municipalities, and political subdivisions	$	3,892	$	174	$	—	$	4,066
Total	$	3,892	$	174	$	—	$	4,066

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

Summary of Gross Unrealized Losses and Fair Values, Aggregated by Investment Category and Length of Individual Securities Continuous Unrealized Loss Position Available-for-sale and Held to Maturity

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	)

Summary of Proceeds From Sales of Securities Available-for-sale and Associated Gains and Losses

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:

	For the Three Months Ended
	March 31,
	2021		2020
Proceeds	$	89,301	$	45,417
Gross gains		1,626		1,457
Gross losses		164		82

Schedule of Amortized Cost and Fair Value of Debt Securities by Contractual Maturity

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