Securities (Tables)

3 Months Ended

Mar. 31, 2020

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			Allowance
	Amortized		Unrealized		Unrealized			for Credit	Fair
March 31, 2020:	Cost		Gains		Losses			Losses	Value
Debt securities available for sale
U.S. Treasury securities	$	44,545	$	849	$	—	$	—	$	45,394
Obligations of U.S. government corporations and agencies		87,787		2,829		(42)		—		90,574
Obligations of states and political subdivisions		278,741		6,359		(353)		—		284,747
Commercial mortgage-backed securities		239,284		6,139		(2)		—		245,421
Residential mortgage-backed securities		966,805		34,071		(19)		—		1,000,857
Corporate debt securities		99,061		528		(637)		—		98,952
Total	$	1,716,223	$	50,775	$	(1,053)	$	—	$	1,765,945

			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
December 31, 2019:	Cost		Gains		Losses		Value
Debt securities available for sale
U.S. Treasury securities	$	51,472	$	265	$	—	$	51,737
Obligations of U.S. government corporations and agencies		160,364		2,684		(48)		163,000
Obligations of states and political subdivisions		262,492		5,810		(11)		268,291
Commercial mortgage-backed securities		137,733		1,700		(146)		139,287
Residential mortgage-backed securities		912,308		10,282		(624)		921,966
Corporate debt securities		102,696		1,280		—		103,976
Total	$	1,627,065	$	22,021	$	(829)	$	1,648,257

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

The amortized cost and fair value of debt securities, by contractual maturity or pre-refunded date, are shown below. Mortgages underlying mortgage-backed securities may be called or prepaid; therefore, actual maturities could differ from the contractual maturities. All mortgage-backed securities were issued by U.S. government agencies and corporations (dollars in thousands).

	Debt securities available for sale
	Amortized		Fair
March 31, 2020:	Cost		Value
Due in one year or less	$	142,273	$	142,758
Due after one year through five years		275,344		282,349
Due after five years through ten years		244,765		252,843
Due after ten years		1,053,841		1,087,995
Total	$	1,716,223	$	1,765,945

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,
	2020		2019
Gross security gains	$	1,561	$	—
Gross security (losses)		(5)		(183)
Net gains (losses) on sales of securities(1)	$	1,556	$	(183)

(1) Net (losses) gains on sales of securities reported on the unaudited Consolidated Statements of Income includes sale 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, gross				12 months or more, gross				Total, gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
March 31, 2020:	Value		Losses		Value		Losses		Value		Losses
Debt securities available for sale
U.S. Treasury securities	$	—	$	—	$	—	$	—	$	—	$	—
Obligations of U.S. government corporations and agencies		6,006		(42)		—		—		6,006		(42)
Obligations of states and political subdivisions		15,445		(353)		—		—		15,445		(353)
Commercial mortgage-backed securities		8,522		(2)		—		—		8,522		(2)
Residential mortgage-backed securities		626		(5)		1,417		(14)		2,043		(19)
Corporate debt securities		41,117		(637)		—		—		41,117		(637)
Total temporarily impaired securities	$	71,716	$	(1,039)	$	1,417	$	(14)	$	73,133	$	(1,053)

	Less than 12 months, gross				12 months or more, gross				Total, gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
December 31, 2019:	Value		Losses		Value		Losses		Value		Losses
Debt securities available for sale
U.S. Treasury securities	$	—	$	—	$	—	$	—	$	—	$	—
Obligations of U.S. government corporations and agencies		6,362		(48)		—		—		6,362		(48)
Obligations of states and political subdivisions(1)		4,981		(11)		1,548		—		6,529		(11)
Commercial mortgage-backed securities		33,322		(144)		2,044		(2)		35,366		(146)
Residential mortgage-backed securities		78,326		(245)		50,259		(379)		128,585		(624)
Corporate debt securities		—		—		—		—		—		—
Total temporarily impaired securities	$	122,991	$	(448)	$	53,851	$	(381)	$	176,842	$	(829)

(1) Unrealized losses for 12 months or more, gross, was less than one thousand dollars.