NOTE D:

INVESTMENT SECURITIES

The amortized cost and estimated fair value of investment securities as of September 30, 2018 and December 31, 2017 are as follows:

	September 30, 2018								December 31, 2017
(000's omitted)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Available-for-Sale Portfolio:
U.S. Treasury and agency securities	$	2,039,086	$	0	$	40,991	$	1,998,095	$	2,043,023	$	15,886	$	4,838	$	2,054,071
Obligations of state and political subdivisions		473,048		5,250		2,933		475,365		514,949		14,064		57		528,956
Government agency mortgage-backed securities		369,970		1,297		13,204		358,063		358,180		3,121		3,763		357,538
Corporate debt securities		2,603		0		53		2,550		2,648		0		25		2,623
Government agency collateralized mortgage obligations		73,112		25		2,431		70,706		88,097		155		878		87,374
Marketable equity securities		0		0		0		0		251		275		0		526
Total available-for-sale portfolio	$	2,957,819	$	6,572	$	59,612	$	2,904,779	$	3,007,148	$	33,501	$	9,561	$	3,031,088

Equity and other Securities:
Equity securities, at fair value	$	251	$	247	$	0	$	498	$	0	$	0	$	0	$	0
Federal Home Loan Bank common stock		6,343		0		0		6,343		9,896		0		0		9,896
Federal Reserve Bank common stock		30,690		0		0		30,690		30,690		0		0		30,690
Certificates of deposit		0		0		0		0		3,865		0		0		3,865
Other equity securities, at cost		4,997		750		0		5,747		5,840		0		0		5,840
Total equity and other securities	$	42,281	$	997	$	0	$	43,278	$	50,291	$	0	$	0	$	50,291

A summary of investment securities that have been in a continuous unrealized loss position is as follows:

As of September 30, 2018

	Less than 12 Months						12 Months or Longer						Total
(000's omitted)		#	Fair Value		Gross Unrealized Losses			#	Fair Value		Gross Unrealized Losses			#	Fair Value		Gross Unrealized Losses

Available-for-Sale Portfolio:
U.S. Treasury and agency securities		50	$	1,633,859	$	30,625		32	$	364,236	$	10,366		82	$	1,998,095	$	40,991
Obligations of state and political subdivisions		333		171,781		2,619		9		5,913		314		342		177,694		2,933
Government agency mortgage-backed securities		89		128,752		3,783		136		178,871		9,421		225		307,623		13,204
Corporate debt securities		0		0		0		1		2,550		53		1		2,550		53
Government agency collateralized mortgage obligations		12		8,371		199		36		59,825		2,232		48		68,196		2,431
Total available-for-sale investment portfolio		484	$	1,942,763	$	37,226		214	$	611,395	$	22,386		698	$	2,554,158	$	59,612

As of December 31, 2017

	Less than 12 Months						12 Months or Longer						Total
(000's omitted)		#	Fair Value		Gross Unrealized Losses			#	Fair Value		Gross Unrealized Losses			#	Fair Value		Gross Unrealized Losses

Available-for-Sale Portfolio:
U.S. Treasury and agency securities		44	$	699,709	$	4,838		0	$	0	$	0		44	$	699,709	$	4,838
Obligations of state and political subdivisions		45		23,432		57		0		0		0		45		23,432		57
Government agency mortgage-backed securities		120		185,716		1,433		55		75,712		2,330		175		261,428		3,763
Corporate debt securities		1		2,623		25		0		0		0		1		2,623		25
Government agency collateralized mortgage obligations		39		80,041		878		1		1		0		40		80,042		878
Total available-for-sale investment portfolio		249	$	991,521	$	7,231		56	$	75,713	$	2,330		305	$	1,067,234	$	9,561

The unrealized losses reported pertaining to securities issued by the U.S. government and its sponsored entities, include treasuries, agencies, and mortgage-backed securities issued by Ginnie Mae, Fannie Mae, and Freddie Mac, which are currently rated AAA by Moody’s Investor Services, AA+ by Standard & Poor’s and are guaranteed by the U.S. government. The majority of the obligations of state and political subdivisions and corporations carry a credit rating of A or better. Additionally, a majority of the obligations of state and political subdivisions carry a secondary level of credit enhancement. The Company does not intend to sell these securities, nor is it more likely than not that the Company will be required to sell these securities prior to recovery of the amortized cost. The unrealized losses in the portfolios are primarily attributable to changes in interest rates. As such, management does not believe any individual unrealized loss as of September 30, 2018 represents OTTI.

The amortized cost and estimated fair value of debt securities at September 30, 2018, by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Securities not due at a single maturity date are shown separately.

	Available-for-Sale
(000's omitted)	Amortized Cost		Fair Value
Due in one year or less	$	61,112	$	60,985
Due after one through five years		2,020,525		1,985,501
Due after five years through ten years		274,222		270,449
Due after ten years		158,878		159,075
Subtotal		2,514,737		2,476,010
Government agency mortgage-backed securities		369,970		358,063
Government agency collateralized mortgage obligations		73,112		70,706
Total	$	2,957,819	$	2,904,779

As of September 30, 2018, $289.0 million of U.S. Treasury securities were pledged as collateral for securities sold under agreement to repurchase. All securities sold under agreement to repurchase as of September 30, 2018 have an overnight and continuous maturity.