Investment Securities (Tables)

6 Months Ended

Jun. 30, 2019

Investments, Debt and Equity Securities [Abstract]

Schedule of amortized cost, gross unrealized gains, gross unrealized losses and approximate fair value of investment securities

The amortized cost, gross unrealized gains, gross unrealized losses and approximate market value of the Corporation's investment securities at the dates indicated were:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Available for sale at June 30, 2019
U.S. Government-sponsored agency securities	$	33,494	$	453	$	—	$	33,947
State and municipal	685,123		30,835		200		715,758
U.S. Government-sponsored mortgage-backed securities	642,298		8,532		607		650,223
Corporate obligations	31		—		—		31
Total available for sale	1,360,946		39,820		807		1,399,959
Held to maturity at June 30, 2019
U.S. Government-sponsored agency securities	33,865		20		66		33,819
State and municipal	310,076		10,987		22		321,041
U.S. Government-sponsored mortgage-backed securities	347,524		5,257		226		352,555
Foreign investment	1,500		—		—		1,500
Total held to maturity	692,965		16,264		314		708,915
Total Investment Securities	$	2,053,911	$	56,084	$	1,121	$	2,108,874

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Available for sale at December 31, 2018
U.S. Government-sponsored agency securities	$	13,493	$	92	$	3	$	13,582
State and municipal	605,994		5,995		5,854		606,135
U.S. Government-sponsored mortgage-backed securities	530,209		634		8,396		522,447
Corporate obligations	31		—		—		31
Total available for sale	1,149,727		6,721		14,253		1,142,195
Held to maturity at December 31, 2018
U.S. Government-sponsored agency securities	22,618		—		545		22,073
State and municipal	197,909		2,858		872		199,895
U.S. Government-sponsored mortgage-backed securities	268,860		713		3,323		266,250
Foreign investment	1,000		—		1		999
Total held to maturity	490,387		3,571		4,741		489,217
Total Investment Securities	$	1,640,114	$	10,292	$	18,994	$	1,631,412

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

The amortized cost and fair value of available for sale and held to maturity securities at June 30, 2019 and December 31, 2018, by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties.

	Available for Sale				Held to Maturity
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Maturity Distribution at June 30, 2019:
Due in one year or less	$	1,131	$	1,138	$	3,784	$	3,782
Due after one through five years	3,752		3,851		46,941		46,914
Due after five through ten years	74,311		76,604		78,716		81,769
Due after ten years	639,454		668,143		216,000		223,895
	718,648		749,736		345,441		356,360
U.S. Government-sponsored mortgage-backed securities	642,298		650,223		347,524		352,555
Total Investment Securities	$	1,360,946	$	1,399,959	$	692,965	$	708,915

	Available for Sale				Held to Maturity
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Maturity Distribution at December 31, 2018
Due in one year or less	$	13,092	$	13,144	$	4,732	$	4,730
Due after one through five years	5,311		5,378		49,054		48,473
Due after five through ten years	73,280		74,411		62,873		64,163
Due after ten years	527,835		526,815		104,868		105,601
	619,518		619,748		221,527		222,967
U.S. Government-sponsored mortgage-backed securities	530,209		522,447		268,860		266,250
Total Investment Securities	$	1,149,727	$	1,142,195	$	490,387	$	489,217

Schedule of gross gains on sales and redemptions of available for sale securities

Gross gains on the sales and redemptions of available for sale securities for the three and six months ended June 30, 2019 and 2018 are shown below.

	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Sales and Redemptions of Available for Sale Securities:
Gross gains	$	1,843	$	1,122	$	2,983	$	2,731
Gross losses	—		—		—		—

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

The following tables show the Corporation’s gross unrealized losses and fair value, aggregated by investment category and length of time the individual securities have been in a continuous unrealized loss position at June 30, 2019, and December 31, 2018:

	Less than 12 Months				12 Months or Longer				Total
	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Temporarily Impaired Available for Sale Securities at June 30, 2019
State and municipal	$	7,699	$	16	$	7,080	$	184	$	14,779	$	200
U.S. Government-sponsored mortgage-backed securities	7,791		15		75,152		592		82,943		607
Total Temporarily Impaired Available for Sale Securities	15,490		31		82,232		776		97,722		807
Temporarily Impaired Held to Maturity Securities at June 30, 2019
U.S. Government-sponsored agency securities	—		—		15,454		66		15,454		66
State and municipal	6,421		22		—		—		6,421		22
U.S. Government-sponsored mortgage-backed securities	74		—		36,614		226		36,688		226
Total Temporarily Impaired Held to Maturity Securities	6,495		22		52,068		292		58,563		314
Total Temporarily Impaired Investment Securities	$	21,985	$	53	$	134,300	$	1,068	$	156,285	$	1,121

	Less than 12 Months				12 Months or Longer				Total
	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Temporarily Impaired Available for Sale Securities at December 31, 2018
U.S. Government-sponsored agency securities	$	1,490	$	3	$	—	$	—	$	1,490	$	3
State and municipal	234,431		3,958		38,028		1,896		272,459		5,854
U.S. Government-sponsored mortgage-backed securities	196,601		2,400		217,121		5,996		413,722		8,396
Total Temporarily Impaired Available for Sale Securities	432,522		6,361		255,149		7,892		687,671		14,253
Temporarily Impaired Held to Maturity Securities at December 31, 2018
U.S. Government-sponsored agency securities	—		—		22,073		545		22,073		545
State and municipal	14,952		369		16,786		503		31,738		872
U.S. Government-sponsored mortgage-backed securities	102,828		876		87,268		2,447		190,096		3,323
Foreign investment	—		—		999		1		999		1
Total Temporarily Impaired Held to Maturity Securities	117,780		1,245		127,126		3,496		244,906		4,741
Total Temporarily Impaired Investment Securities	$	550,302	$	7,606	$	382,275	$	11,388	$	932,577	$	18,994

Schedule of investments in debt and equity securities reported in the financial statements at an amount less than their historical cost

Certain investments in debt and equity securities are reported in the financial statements at an amount less than their historical cost as indicated in the table below.

	June 30, 2019			December 31, 2018
Investments reported at less than historical cost:
Historical cost	$	157,406		$	951,571
Fair value	156,285			932,577
Gross unrealized losses	$	1,121		$	18,994
Percent of the Corporation's investment portfolio	7.5		%	57.1		%