Investment Securities (Tables)

9 Months Ended

Sep. 30, 2018

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 September 30, 2018
U.S. Government-sponsored agency securities	$	18,492			$	134	$	18,358
State and municipal	611,528		2,920		14,280		600,168
U.S. Government-sponsored mortgage-backed securities	547,223		71		16,689		530,605
Corporate obligations	31						31
Total available for sale	1,177,274		2,991		31,103		1,149,162
Held to maturity at September 30, 2018
U.S. Government-sponsored agency securities	22,618				833		21,785
State and municipal	192,124		1,161		1,748		191,537
U.S. Government-sponsored mortgage-backed securities	260,347		300		6,514		254,133
Foreign Investments	1,000				3		997
Total held to maturity	476,089		1,461		9,098		468,452
Total Investment Securities	$	1,653,363	$	4,452	$	40,201	$	1,617,614

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Available for sale at December 31, 2017
State and municipal	$	510,852	$	16,932	$	1,091	$	526,693
U.S. Government-sponsored mortgage-backed securities	473,325		964		3,423		470,866
Corporate obligations	31						31
Equity securities	2,357						2,357
Total available for sale	986,565		17,896		4,514		999,947
Held to maturity at December 31, 2017
U.S. Government-sponsored agency securities	22,618				435		22,183
State and municipal	235,594		6,295		244		241,645
U.S. Government-sponsored mortgage-backed securities	301,443		3,341		1,404		303,380
Foreign Investment	1,000						1,000
Total held to maturity	560,655		9,636		2,083		568,208
Total Investment Securities	$	1,547,220	$	27,532	$	6,597	$	1,568,155

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 September 30, 2018 and December 31, 2017, 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 September 30, 2018:
Due in one year or less	$	24,098	$	24,360	$	5,161	$	5,178
Due after one through five years	17,294		17,511		48,155		47,042
Due after five through ten years	75,416		75,498		57,950		58,212
Due after ten years	513,243		501,188		104,476		103,887
	630,051		618,557		215,742		214,319
U.S. Government-sponsored mortgage-backed securities	547,223		530,605		260,347		254,133
Total Investment Securities	$	1,177,274	$	1,149,162	$	476,089	$	468,452

	Available for Sale				Held to Maturity
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Maturity Distribution at December 31, 2017
Due in one year or less	$	425	$	425	$	12,015	$	12,158
Due after one through five years	5,040		5,204		76,146		76,334
Due after five through ten years	74,921		78,806		54,441		55,679
Due after ten years	430,497		442,289		116,610		120,657
	510,883		526,724		259,212		264,828
U.S. Government-sponsored mortgage-backed securities	473,325		470,866		301,443		303,380
Equity securities	2,357		2,357
Total Investment Securities	$	986,565	$	999,947	$	560,655	$	568,208

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 nine months ended September 30, 2018 and 2017 are shown below.

	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Sales and Redemptions of Available for Sale Securities:
Gross gains	$	1,285	$	382	$	4,016	$	1,547
Gross losses			50				50

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 September 30, 2018, and December 31, 2017:

	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 September 30, 2018
U.S. Government-sponsored agency securities	$	18,358	$	134					$	18,358	$	134
State and municipal	397,852		11,780		$	30,820	$	2,500	428,672		14,280
U.S. Government-sponsored mortgage-backed securities	386,632		9,603		134,602		7,086		521,234		16,689
Total Temporarily Impaired Available for Sale Securities	802,842		21,517		165,422		9,586		968,264		31,103
Temporarily Impaired Held to Maturity Securities at September 30, 2018
U.S. Government-sponsored agency securities	97		3		21,688		830		21,785		833
State and municipal	44,857		857		16,326		891		61,183		1,748
U.S. Government-sponsored mortgage-backed securities	168,488		3,473		61,139		3,041		229,627		6,514
Corporate Obligations	997		3						997		3
Total Temporarily Impaired Held to Maturity Securities	214,439		4,336		99,153		4,762		313,592		9,098
Total Temporarily Impaired Investment Securities	$	1,017,281	$	25,853	$	264,575	$	14,348	$	1,281,856	$	40,201

	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, 2017
State and municipal	$	13,296	$	198	$	35,324	$	893	$	48,620	$	1,091
U.S. Government-sponsored mortgage-backed securities	182,755		1,520		68,667		1,903		251,422		3,423
Total Temporarily Impaired Available for Sale Securities	196,051		1,718		103,991		2,796		300,042		4,514
Temporarily Impaired Held to Maturity Securities at December 31, 2017
U.S. Government-sponsored agency securities	9,988		131		12,196		304		22,184		435
State and municipal	2,430		36		15,805		208		18,235		244
U.S. Government-sponsored mortgage-backed securities	62,508		485		43,078		919		105,586		1,404
Total Temporarily Impaired Held to Maturity Securities	74,926		652		71,079		1,431		146,005		2,083
Total Temporarily Impaired Investment Securities	$	270,977	$	2,370	$	175,070	$	4,227	$	446,047	$	6,597

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.

	September 30, 2018			December 31, 2017
Investments reported at less than historical cost:
Historical cost	$	1,322,058		$	452,644
Fair value	$	1,281,856		$	446,047
Percent of the Corporation's investment portfolio	78.9		%	28.6		%