Investment Securities (Tables)

3 Months Ended

Mar. 31, 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 March 31, 2018
U.S. Government-sponsored agency securities	$	6,491	$	8	$	1	$	6,498
State and municipal	510,884		6,588		7,238		510,234
U.S. Government-sponsored mortgage-backed securities	496,824		251		10,039		487,036
Corporate obligations	31						31
Total available for sale	1,014,230		6,847		17,278		1,003,799
Held to maturity at March 31, 2018
U.S. Government-sponsored agency securities	22,619				715		21,904
State and municipal	228,620		2,784		911		230,493
U.S. Government-sponsored mortgage-backed securities	287,782		988		3,762		285,008
Foreign Investments	1,000				6		994
Total held to maturity	540,021		3,772		5,394		538,399
Total Investment Securities	$	1,554,251	$	10,619	$	22,672	$	1,542,198

	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 March 31, 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 March 31, 2018:
Due in one year or less	$	544	$	549	$	18,366	$	18,675
Due after one through five years	4,982		5,064		68,198		67,756
Due after five through ten years	81,890		83,630		52,976		53,437
Due after ten years	429,990		427,520		112,699		113,523
	517,406		516,763		252,239		253,391
U.S. Government-sponsored mortgage-backed securities	496,824		487,036		287,782		285,008
Total Investment Securities	$	1,014,230	$	1,003,799	$	540,021	$	538,399

	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 months ended March 31, 2018 and 2017 are shown below.

	Three Months Ended March 31,
	2018		2017
Sales and Redemptions of Available for Sale Securities:
Gross gains	$	1,609	$	598
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 March 31, 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 March 31, 2018
U.S. Government-sponsored agency securities	$	371	$	1					$	371	$	1
State and municipal	236,539		5,298		$	28,126	$	1,940	264,665		7,238
U.S. Government-sponsored mortgage-backed securities	385,626		6,956		65,490		3,083		451,116		10,039
Total Temporarily Impaired Available for Sale Securities	622,536		12,255		93,616		5,023		716,152		17,278
Temporarily Impaired Held to Maturity Securities at March 31, 2018
U.S. Government-sponsored agency securities	9,861		258		12,043		457		21,904		715
State and municipal	18,155		307		15,388		604		33,543		911
U.S. Government-sponsored mortgage-backed securities	177,080		2,154		40,866		1,608		217,946		3,762
Corporate Obligations	994		6						994		6
Total Temporarily Impaired Held to Maturity Securities	206,090		2,725		68,297		2,669		274,387		5,394
Total Temporarily Impaired Investment Securities	$	828,626	$	14,980	$	161,913	$	7,692	$	990,539	$	22,672

	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.

	March 31, 2018			December 31, 2017
Investments reported at less than historical cost:
Historical cost	$	1,013,210		$	452,644
Fair value	$	990,539		$	446,047
Percent of the Corporation's investment portfolio	64.2		%	28.6		%