Investment Securities (Tables)

12 Months Ended

Dec. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Approximate Market Value of 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 December 31, 2016
U.S. Government-sponsored agency securities	$	100					$	100
State and municipal	360,779		$	8,443	$	5,564	363,658
U.S. Government-sponsored mortgage-backed securities	313,459		1,904		3,071		312,292
Corporate obligations	31						31
Equity securities	21,820				1,039		20,781
Total available for sale	696,189		10,347		9,674		696,862
Held to maturity at December 31, 2016
U.S. Government-sponsored agency securities	22,619				479		22,140
State and municipal	224,811		3,136		1,796		226,151
U.S. Government-sponsored mortgage-backed securities	360,213		4,956		1,527		363,642
Total held to maturity	607,643		8,092		3,802		611,933
Total Investment Securities	$	1,303,832	$	18,439	$	13,476	$	1,308,795
Available for sale at December 31, 2015
U.S. Government-sponsored agency securities	$	100	$	4			$	104
State and municipal	291,730		14,241		$	60	305,911
U.S. Government-sponsored mortgage-backed securities	342,550		4,234		518		346,266
Corporate obligations	31						31
Equity securities	3,912						3,912
Certificates of deposit	2,176						2,176
Total available for sale	640,499		18,479		578		658,400
Held to maturity at December 31, 2015
State and municipal	219,767		6,982		15		226,734
U.S. Government-sponsored mortgage-backed securities	398,832		7,601		787		405,646
Total held to maturity	618,599		14,583		802		632,380
Total Investment Securities	$	1,259,098	$	33,062	$	1,380	$	1,290,780

Debt Securities Credit Loss Recognized in Income, and Other Losses Recorded in Other Comprehensive Income

The following table provides information about debt securities for which only a credit loss was recognized in income and other losses were recorded in other comprehensive income.

	Accumulated Credit Losses in		Accumulated Credit Losses in
	2016		2015
Credit losses on debt securities held:
Balance, January 1	$	—	$	500
Reductions for previous other-than-temporary losses realized on securities sold during the year	—		$	(500	)
Balance, December 31	$	—	$	—

Investments' Gross Unrealized Losses and Fair Value Aggregated by Investment Category and Length of Time in Continuous Unrealized Loss Position

The following table shows 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 December 31, 2016 and 2015: 

	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, 2016
State and municipal	$	126,593	$	5,564					$	126,593	$	5,564
U.S. Government-sponsored mortgage-backed securities	185,544		3,071						185,544		3,071
Equity securities	18,765		1,039						18,765		1,039
Total Temporarily Impaired Available for Sale Securities	330,902		9,674						330,902		9,674
Temporarily Impaired Held to Maturity Securities at December 31, 2016
U.S. Government-sponsored agency securities	19,121		479						19,121		479
State and municipal	50,897		1,796						50,897		1,796
U.S. Government-sponsored mortgage-backed securities	109,377		1,527						109,377		1,527
Total Temporarily Impaired Held to Maturity Securities	179,395		3,802						179,395		3,802
Total Temporarily Impaired Investment Securities	$	510,297	$	13,476					$	510,297	$	13,476
	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, 2015
State and municipal	$	7,558	$	60					$	7,558	$	60
U.S. Government-sponsored mortgage-backed securities	83,396		445		$	2,101	$	73	85,497		518
Total Temporarily Impaired Available for Sale Securities	90,954		505		2,101		73		93,055		578
Temporarily Impaired Held to Maturity Securities at December 31, 2015
State and municipal					1,982		15		1,982		15
U.S. Government-sponsored mortgage-backed securities	69,641		519		12,906		268		82,547		787
Total Temporarily Impaired Held to Maturity Securities	69,641		519		14,888		283		84,529		802
Total Temporarily Impaired Investment Securities	$	160,595	$	1,024	$	16,989	$	356	$	177,584	$	1,380

Amortized Cost and Fair Value of Available for Sale Securities and Held to Maturity Securities by Contractual Maturity

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 December 31, 2016
Due in one year or less	$	2,703	$	2,717	$	2,046	$	2,047
Due after one through five years	16,359		17,068		61,921		63,193
Due after five through ten years	60,614		62,241		61,606		61,145
Due after ten years	281,234		281,763		121,857		121,906
	360,910		363,789		247,430		248,291
U.S. Government-sponsored mortgage-backed securities	313,459		312,292		360,213		363,642
Equity securities	21,820		20,781
Total Investment Securities	$	696,189	$	696,862	$	607,643	$	611,933