INVESTMENT SECURITIES (Tables)

6 Months Ended

Jun. 30, 2018

INVESTMENT SECURITIES [Abstract]

Amortized Cost and Estimated Fair Value of Investment Securities

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

	June 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	$	2,042,116	$	477	$	28,631	$	2,013,962	$	2,043,023	$	15,886	$	4,838	$	2,054,071
Obligations of state and political subdivisions		485,099		7,825		1,440		491,484		514,949		14,064		57		528,956
Government agency mortgage-backed securities		364,919		1,724		10,746		355,897		358,180		3,121		3,763		357,538
Corporate debt securities		2,618		0		55		2,563		2,648		0		25		2,623
Government agency collateralized mortgage obligations		78,137		52		2,151		76,038		88,097		155		878		87,374
Marketable equity securities		0		0		0		0		251		275		0		526
Total available-for-sale portfolio	$	2,972,889	$	10,078	$	43,023	$	2,939,944	$	3,007,148	$	33,501	$	9,561	$	3,031,088
Equity and other Securities:
Equity securities, at fair value	$	251	$	253	$	0	$	504	$	0	$	0	$	0	$	0
Federal Home Loan Bank common stock		6,371		0		0		6,371		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		5,843		0		0		5,843		5,840		0		0		5,840
Total equity and other securities	$	43,155	$	253	$	0	$	43,408	$	50,291	$	0	$	0	$	50,291

Summary of Investment Securities That Have Been in a Continuous Unrealized Loss Position for Less Than or Greater Than Twelve Months

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

As of June 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		77	$	1,924,896	$	28,567		3	$	14,945	$	64		80	$	1,939,841	$	28,631
Obligations of state and political subdivisions		224		111,946		1,440		0		0		0		224		111,946		1,440
Government agency mortgage-backed securities		135		213,903		5,885		77		85,735		4,861		212		299,638		10,746
Corporate debt securities		1		2,563		55		0		0		0		1		2,563		55
Government agency collateralized mortgage obligations		32		58,808		1,868		9		11,419		283		41		70,227		2,151
Total available-for-sale investment portfolio		469	$	2,312,116	$	37,815		89	$	112,099	$	5,208		558	$	2,424,215	$	43,023

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

Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity

The amortized cost and estimated fair value of debt securities at June 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	$	63,241	$	63,194
Due after one through five years		1,884,323		1,861,933
Due after five years through ten years		414,137		412,375
Due after ten years		168,132		170,507
Subtotal		2,529,833		2,508,009
Government agency mortgage-backed securities		364,919		355,897
Government agency collateralized mortgage obligations		78,137		76,038
Total	$	2,972,889	$	2,939,944