Note 2 - Securities

Year-end securities held to maturity and available for sale consisted of the following:


	2011								2010
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value


Securities Held to Maturity:
U.S. Treasury	$	247,797	$	31,715	$	-	$	279,512	$	247,421	$	13,517	$	-	$	260,938
Residential mortgage-backed securities		11,874		153		-		12,027		4,405		136		-		4,541
States and political subdivisions		105,325		6,597		-		111,922		30,803		-		1,054		29,749
Other		1,000		-		-		1,000		1,000		-		-		1,000

Total	$	365,996	$	38,465	$	-	$	404,461	$	283,629	$	13,653	$	1,054	$	296,228


Securities Available for Sale:
U. S. Treasury	$	2,020,621	$	36,111	$	-	$	2,056,732	$	973,033	$	13,998	$	-	$	987,031
U.S. government agencies/corporations		250,000		884		-		250,884		-		-		-		-
Residential mortgage-backed securities		3,135,064		154,386		180		3,289,270		1,989,299		103,018		987		2,091,330
States and political subdivisions		1,996,703		158,133		23		2,154,813		2,008,618		53,358		21,676		2,040,300
Other		38,001		-		-		38,001		38,809		-		-		38,809

Total	$	7,440,389	$	349,514	$	203	$	7,789,700	$	5,009,759	$	170,374	$	22,663	$	5,157,470

All mortgage-backed securities included in the above table were issued by U.S. government agencies and corporations. Securities with limited marketability, such as stock in the Federal Reserve Bank and the Federal Home Loan Bank, are carried at cost and are reported as other available for sale securities in the table above. The carrying value of securities pledged to secure public funds, trust deposits, repurchase agreements and for other purposes, as required or permitted by law was $2.4 billion and $2.3 billion at December 31, 2011 and 2010.

Year-end securities with unrealized losses, segregated by length of impairment, were as follows:


	Less than 12 Months				More than 12 Months				Total
	Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses


2011
Available for Sale
Residential mortgage-backed securities	$	103,258	$	180	$	-	$	-	$	103,258	$	180
States and political subdivisions		-		-		1,164		23		1,164		23

Total	$	103,258	$	180	$	1,164	$	23	$	104,422	$	203

2010
Held to Maturity
States and political subdivisions	$	29,749	$	1,054	$	-	$	-	$	29,749	$	1,054

Total	$	29,749	$	1,054	$	-	$	-	$	29,749	$	1,054

Available for Sale
Residential mortgage-backed securities	$	101,141	$	987	$	-	$	-	$	101,141	$	987
States and political subdivisions		855,428		21,521		1,346		155		856,774		21,676

Total	$	956,569	$	22,508	$	1,346	$	155	$	957,915	$	22,663

Declines in the fair value of held-to-maturity and available-for-sale securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses to the extent the impairment is related to credit losses. The amount of the impairment related to other factors is recognized in other comprehensive income. In estimating other-than-temporary impairment losses, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer, and (iii) the intent and ability of the Corporation to retain its investment in the issuer for a period of time sufficient to allow for any anticipated recovery in cost.

Management has the ability and intent to hold the securities classified as held to maturity in the table above until they mature, at which time the Corporation will receive full value for the securities. Furthermore, as of December 31, 2011, management does not have the intent to sell any of the securities classified as available for sale in the table above and believes that it is more likely than not that the Corporation will not have to sell any such securities before a recovery of cost. Any unrealized losses are largely due to increases in market interest rates over the yields available at the time the underlying securities were purchased. The fair value is expected to recover as the bonds approach their maturity date or repricing date or if market yields for such investments decline. Management does not believe any of the securities are impaired due to reasons of credit quality. Accordingly, as of December 31, 2011, management believes the impairments detailed in the table above are temporary and no impairment loss has been realized in the Corporation's consolidated income statement.

The amortized cost and estimated fair value of securities, excluding trading securities, at December 31, 2011 are presented below by contractual maturity. Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations. Residential mortgage-backed securities and equity securities are shown separately since they are not due at a single maturity date.


	Held to Maturity				Available for Sale
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value

Due in one year or less	$	-	$	-	$	41,078	$	41,306
Due after one year through five years		1,000		1,000		2,342,618		2,384,191
Due after five years through ten years		251,126		283,161		195,338		211,452
Due after ten years		101,996		108,273		1,688,290		1,825,480
Residential mortgage-backed securities		11,874		12,027		3,135,064		3,289,270
Equity securities		-		-		38,001		38,001

Total	$	365,996	$	404,461	$	7,440,389	$	7,789,700

Sales of securities available for sale were as follows:


	2011			2010			2009

Proceeds from sales	$	5,587,391		$	9,997,994		$	206,477
Gross realized gains		6,418			8			283
Gross realized losses		(4	)		(2	)		(1,543	)
Tax (expense) benefit of securities gains/losses		(2,245	)		(2	)		441

Year-end trading account securities, at estimated fair value, were as follows:


	2011		2010

U.S. Treasury	$	13,609	$	14,986
States and political subdivisions		-		115

Total	$	13,609	$	15,101

Net gains and losses on trading account securities were as follows:


	Year Ended December 31,
	2011			2010		2009

Net gain on sales transactions	$	1,607		$	1,688	$	1,887
Net mark-to-market gains (losses)		(15	)		145		101

Net gain on trading account securities	$	1,592		$	1,833	$	1,988