Securities (Tables)

3 Months Ended

Mar. 31, 2021

Securities

Schedule of amortized cost, unrealized gains and losses and fair values of securities classified available for sale and held to maturity

The table below provides the amortized cost, unrealized gains and losses, and fair values of debt securities summarized by major category (dollars in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized				Fair
March 31, 2021:	Cost		Gains		Losses			ACL	Value
U.S. Treasury securities	$	23,514	$	243	$	—	$	—	$	23,757
Obligations of U.S. government corporations and agencies		64,903		1,720		(45)		—		66,578
Obligations of states and political subdivisions		280,150		8,854		(1,542)		—		287,462
Commercial mortgage-backed securities		499,996		5,308		(6,786)		—		498,518
Residential mortgage-backed securities		1,786,062		18,587		(18,329)		—		1,786,320
Corporate debt securities		134,783		964		(1,427)		—		134,320
Debt securities available for sale	$	2,789,408	$	35,676	$	(28,129)	$	—	$	2,796,955

			Gross		Gross
	Amortized		Unrealized		Unrealized				Fair
December 31, 2020:	Cost		Gains		Losses			ACL	Value
U.S. Treasury securities	$	27,481	$	356	$	—	$	—	$	27,837
Obligations of U.S. government corporations and agencies		67,406		2,162		(49)		—		69,519
Obligations of states and political subdivisions		292,940		11,779		(8)		—		304,711
Commercial mortgage-backed securities		408,716		10,212		(312)		—		418,616
Residential mortgage-backed securities		1,344,047		24,571		(303)		—		1,368,315
Corporate debt securities		70,953		1,237		(1)		—		72,189
Debt securities available for sale	$	2,211,543	$	50,317	$	(673)		—	$	2,261,187

Schedule of amortized cost and fair value of debt securities available for sale and held to maturity by contractual maturity

			Gross		Gross
	Amortized		Unrealized		Unrealized				Fair
December 31, 2020:	Cost		Gains		Losses			ACL	Value
U.S. Treasury securities	$	27,481	$	356	$	—	$	—	$	27,837
Obligations of U.S. government corporations and agencies		67,406		2,162		(49)		—		69,519
Obligations of states and political subdivisions		292,940		11,779		(8)		—		304,711
Commercial mortgage-backed securities		408,716		10,212		(312)		—		418,616
Residential mortgage-backed securities		1,344,047		24,571		(303)		—		1,368,315
Corporate debt securities		70,953		1,237		(1)		—		72,189
Debt securities available for sale	$	2,211,543	$	50,317	$	(673)		—	$	2,261,187

Schedule of realized gains and losses related to sales of securities

Realized gains and losses related to sales and calls of debt securities available for sale are summarized as follows (dollars in thousands):

	Three Months Ended March 31,
	2021		2020
Gross security gains	$	25	$	1,561
Gross security (losses)		—		(5)
Net gains (losses) on sales of debt securities (1)	$	25	$	1,556

(1) Net gains (losses) on sales of securities reported on the unaudited Consolidated Statements of Income includes sales of equity securities, excluded in this table.

Schedule of securities with gross unrealized losses aggregated by investment category and length of time that individual securities have been in a continuous loss position

The following information pertains to debt securities with gross unrealized losses, aggregated by investment category and the length of time that individual securities have been in a continuous loss position (dollars in thousands):

	Less than 12 months				12 months or more				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
March 31, 2021:	Value		Losses		Value		Losses		Value		Losses
Debt securities available for sale
Obligations of U.S. government corporations and agencies	$	—	$	—	$	4,695	$	(45)	$	4,695	$	(45)
Obligations of states and political subdivisions		58,555		(1,542)		—		—		58,555		(1,542)
Commercial mortgage-backed securities		314,109		(6,786)		—		—		314,109		(6,786)
Residential mortgage-backed securities		1,019,462		(18,325)		352		(4)		1,019,814		(18,329)
Corporate debt securities		95,164		(1,427)		—		—		95,164		(1,427)
Total temporarily impaired securities	$	1,487,290	$	(28,080)	$	5,047	$	(49)	$	1,492,337	$	(28,129)

	Less than 12 months				12 months or more				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
December 31, 2020:	Value		Losses		Value		Losses		Value		Losses
Debt securities available for sale
Obligations of U.S. government corporations and agencies	$	—	$	—	$	4,957	$	(49)	$	4,957	$	(49)
Obligations of states and political subdivisions		762		(8)		—		—		762		(8)
Commercial mortgage-backed securities		129,655		(312)		—		—		129,655		(312)
Residential mortgage-backed securities		89,997		(300)		139		(3)		90,136		(303)
Corporate debt securities		1,499		(1)		—		—		1,499		(1)
Total temporarily impaired securities	$	221,913	$	(621)	$	5,096	$	(52)	$	227,009	$	(673)