INVESTMENT SECURITIES (Tables)

6 Months Ended

Jun. 30, 2017

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, 2017 and December 31, 2016 are as follows:

 

	June 30, 2017								December 31, 2016
(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	$	2,039,313	$	36,666	$	181	$	2,075,798	$	1,876,358	$	28,522	$	2,118	$	1,902,762
Obligations of state and political subdivisions		556,459		17,080		67		573,472		582,655		13,389		1,054		594,990
Government agency mortgage-backed securities		331,925		4,326		2,804		333,447		232,657		5,040		2,467		235,230
Corporate debt securities		2,678		0		7		2,671		5,716		2		31		5,687
Government agency collateralized mortgage obligations		100,252		294		107		100,439		9,225		310		0		9,535
Marketable equity securities		251		246		0		497		252		200		0		452
Total available-for-sale portfolio	$	3,030,878	$	58,612	$	3,166	$	3,086,324	$	2,706,863	$	47,463	$	5,670	$	2,748,656
Other Securities:
Federal Home Loan Bank common stock	$	18,439					$	18,439	$	12,191					$	12,191
Federal Reserve Bank common stock		19,806						19,806		19,781						19,781
Certificates of deposit		14,450						14,450		0						0
Other equity securities		5,994						5,994		3,764						3,764
Total other securities	$	58,689					$	58,689	$	35,736					$	35,736

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, 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		22	$	181,119	$	181		0	$	0	$	0		22	$	181,119	$	181
Obligations of state and political subdivisions		17		9,528		67		0		0		0		17		9,528		67
Government agency mortgage-backed securities		123		168,879		1,897		17		23,077		907		140		191,956		2,804
Corporate debt securities		1		2,671		7		0		0		0		1		2,671		7
Government agency collateralized mortgage obligations		30		70,273		107		2		2		0		32		70,275		107
Total available-for-sale investment portfolio		193	$	432,470	$	2,259		19	$	23,079	$	907		212	$	455,549	$	3,166

As of December 31, 2016

	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		13	$	449,242	$	2,118		0	$	0	$	0		13	$	449,242	$	2,118
Obligations of state and political subdivisions		197		102,106		1,054		0		0		0		197		102,106		1,054
Government agency mortgage-backed securities		57		83,862		1,637		15		21,788		830		72		105,650		2,467
Corporate debt securities		1		2,677		31		0		0		0		1		2,677		31
Government agency collateralized mortgage obligations		0		0		0		2		2		0		2		2		0
Total available-for-sale investment portfolio		268	$	637,887	$	4,840		17	$	21,790	$	830		285	$	659,677	$	5,670

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, 2017, 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	$	39,223	$	39,463
Due after one through five years		1,382,389		1,406,162
Due after five years through ten years		972,921		995,474
Due after ten years		203,917		210,842
Subtotal		2,598,450		2,651,941
Government agency mortgage-backed securities		331,925		333,447
Government agency collateralized mortgage obligations		100,252		100,439
Total	$	3,030,627	$	3,085,827