Investment Securities

The following is a summary of the amortized cost and fair value of investment securities available-for-sale and investment securities held-to-maturity at June 30, 2015, December 31, 2014 and June 30, 2014:



	Investment Securities Available-for-Sale
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
	(In thousands)
June 30, 2015
U.S. Treasury securities	$	8,270	$	24	$	—	$	8,294
Government sponsored agencies	227,424		683		200		227,907
State and political subdivisions	26,476		503		14		26,965
Residential mortgage-backed securities	213,621		742		1,694		212,669
Collateralized mortgage obligations	167,768		245		981		167,032
Corporate bonds	39,680		76		78		39,678
Preferred stock and trust preferred securities	2,889		272		—		3,161
Total	$	686,128	$	2,545	$	2,967	$	685,706
December 31, 2014
U.S. Treasury securities	$	8,272	$	—	$	13	$	8,259
Government sponsored agencies	263,658		356		511		263,503
State and political subdivisions	45,157		1,087		17		46,227
Residential mortgage-backed securities	240,465		885		1,543		239,807
Collateralized mortgage obligations	145,316		261		1,194		144,383
Corporate bonds	44,930		213		48		45,095
Preferred stock	1,389		201		—		1,590
Total	$	749,187	$	3,003	$	3,326	$	748,864
June 30, 2014
Government sponsored agencies	$	88,503	$	346	$	141	$	88,708
State and political subdivisions	40,165		1,443		—		41,608
Residential mortgage-backed securities	265,673		1,117		1,422		265,368
Collateralized mortgage obligations	154,035		376		1,128		153,283
Corporate bonds	64,979		456		83		65,352
Preferred stock	1,389		267		—		1,656
Total	$	614,744	$	4,005	$	2,774	$	615,975



	Investment Securities Held-to-Maturity
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
	(In thousands)
June 30, 2015
State and political subdivisions	$	469,337	$	4,853	$	7,912	$	466,278
Trust preferred securities	500		—		200		300
Total	$	469,837	$	4,853	$	8,112	$	466,578
December 31, 2014
State and political subdivisions	$	305,913	$	7,294	$	4,557	$	308,650
Trust preferred securities	10,500		—		3,410		7,090
Total	$	316,413	$	7,294	$	7,967	$	315,740
June 30, 2014
State and political subdivisions	$	297,630	$	5,885	$	6,329	$	297,186
Trust preferred securities	10,500		—		3,725		6,775
Total	$	308,130	$	5,885	$	10,054	$	303,961

The majority of the Corporation’s residential mortgage-backed securities and collateralized mortgage obligations are backed by a U.S. government agency (Government National Mortgage Association) or a government sponsored enterprise (Federal Home Loan Mortgage Corporation or Federal National Mortgage Association).

As of December 31, 2014 and June 30, 2014, the Corporation held a $10.0 million trust preferred investment security of Lake Michigan. With the acquisition of Lake Michigan, this investment was settled as of the acquisition date at par.

The following is a summary of the amortized cost and fair value of investment securities at June 30, 2015, by maturity, for both available-for-sale and held-to-maturity investment securities. The maturities of residential mortgage-backed securities and collateralized mortgage obligations are based on scheduled principal payments. The maturities of all other debt securities are based on final contractual maturity.



	June 30, 2015
	Amortized Cost		Fair Value
	(In thousands)
Investment Securities Available-for-Sale:
Due in one year or less	$	198,939	$	198,680
Due after one year through five years	411,399		411,247
Due after five years through ten years	68,583		68,295
Due after ten years	5,818		5,823
Preferred stock	1,389		1,661
Total	$	686,128	$	685,706
Investment Securities Held-to-Maturity:
Due in one year or less	$	55,922	$	56,043
Due after one year through five years	209,886		209,768
Due after five years through ten years	127,398		125,775
Due after ten years	76,631		74,992
Total	$	469,837	$	466,578

The following schedule summarizes information for both available-for-sale and held-to-maturity investment securities with gross unrealized losses at June 30, 2015, December 31, 2014 and June 30, 2014, aggregated by category and length of time that individual securities have been in a continuous unrealized loss position.



	Less Than 12 Months				12 Months or More				Total
	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
	(In thousands)
June 30, 2015
Government sponsored agencies	$	24,789	$	163	$	14,715	$	37	$	39,504	$	200
State and political subdivisions	258,503		5,433		63,584		2,493		322,087		7,926
Residential mortgage-backed securities	187,858		1,592		3,643		102		191,501		1,694
Collateralized mortgage obligations	49,845		155		48,881		826		98,726		981
Corporate bonds	9,670		49		14,971		29		24,641		78
Trust preferred securities	—		—		300		200		300		200
Total	$	530,665	$	7,392	$	146,094	$	3,687	$	676,759	$	11,079
December 31, 2014
U.S. Treasury securities	$	8,259	$	13	$	—	$	—	$	8,259	$	13
Government sponsored agencies	166,963		406		31,927		105		198,890		511
State and political subdivisions	62,310		3,348		36,847		1,226		99,157		4,574
Residential mortgage-backed securities	17,276		52		180,194		1,491		197,470		1,543
Collateralized mortgage obligations	63,077		179		31,620		1,015		94,697		1,194
Corporate bonds	—		—		14,952		48		14,952		48
Trust preferred securities	—		—		7,090		3,410		7,090		3,410
Total	$	317,885	$	3,998	$	302,630	$	7,295	$	620,515	$	11,293
June 30, 2014
Government sponsored agencies	$	2,377	$	2	$	44,786	$	139	$	47,163	$	141
State and political subdivisions	92,279		4,047		71,421		2,282		163,700		6,329
Residential mortgage-backed securities	10,144		60		197,042		1,362		207,186		1,422
Collateralized mortgage obligations	47,142		68		35,722		1,060		82,864		1,128
Corporate bonds	4,996		5		14,922		78		19,918		83
Trust preferred securities	—		—		6,775		3,725		6,775		3,725
Total	$	156,938	$	4,182	$	370,668	$	8,646	$	527,606	$	12,828

An assessment is performed quarterly by the Corporation to determine whether unrealized losses in its investment securities portfolio are temporary or other-than-temporary by carefully considering all available information. The Corporation reviews factors such as financial statements, credit ratings, news releases and other pertinent information of the underlying issuer or company to make its determination. Management did not believe any individual unrealized loss on any investment security, as of June 30, 2015, represented an other-than-temporary impairment (OTTI). Management believed that the unrealized losses on investment securities at June 30, 2015 were temporary in nature and due primarily to changes in interest rates and reduced market liquidity and not as a result of credit-related issues.

At June 30, 2015, the Corporation did not have the intent to sell any of its impaired investment securities and believed that it was more-likely-than-not that the Corporation will not have to sell any such investment securities before a full recovery of amortized cost. Accordingly, at June 30, 2015, the Corporation believed the impairments in its investment securities portfolio were temporary in nature. However, there is no assurance that OTTI may not occur in the future.