Note 2 – Securities

A summary of the amortized cost and estimated fair value of securities, excluding trading securities, is presented below.


	March 31, 2012								December 31, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held to Maturity
U. S. Treasury	$	247,893	$	29,275	$	—	$	277,168	$	247,797	$	31,715	$	—	$	279,512
Residential mortgage-backed securities		11,547		178		—		11,725		11,874		153		—		12,027
States and political subdivisions		105,163		7,773		—		112,936		105,325		6,597		—		111,922
Other		1,000		—		—		1,000		1,000		—		—		1,000

Total	$	365,603	$	37,226	$	—	$	402,829	$	365,996	$	38,465	$	—	$	404,461

Available for Sale:
U. S. Treasury	$	3,018,660	$	29,607	$	219	$	3,048,048	$	2,020,621	$	36,111	$	—	$	2,056,732
U.S. government agencies/corporations		250,000		782		—		250,782		250,000		884		—		250,884
Residential mortgage-backed securities		2,967,744		156,222		1		3,123,965		3,135,064		154,386		180		3,289,270
States and political subdivisions		1,942,118		165,320		27		2,107,411		1,996,703		158,133		23		2,154,813
Other		38,009		—		—		38,009		38,001		—		—		38,001

Total	$	8,216,531	$	351,931	$	247	$	8,568,215	$	7,440,389	$	349,514	$	203	$	7,789,700

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 above table. 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 $2.2 billion at March 31, 2012 and $2.4 billion and December 31, 2011.

As of March 31, 2012, 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
Available for Sale
U.S. Treasury	$	250,332	$	219	$	—	$	—	$	250,332	$	219
Residential mortgage-backed securities		16		—		49		1		65		1
States and political subdivisions		2,225		27		—		—		2,225		27

Total	$	252,573	$	246	$	49	$	1	$	252,622	$	247

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 March 31, 2012, 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 March 31, 2012, 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 March 31, 2012 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	$	1,000	$	1,000	$	14,850	$	15,125
Due after one year through five years		247,893		277,168		3,360,602		3,396,548
Due after five years through ten years		3,320		3,623		208,835		224,491
Due after ten years		101,843		109,313		1,626,491		1,770,077
Residential mortgage-backed securities		11,547		11,725		2,967,744		3,123,965
Equity securities		—		—		38,009		38,009

Total	$	365,603	$	402,829	$	8,216,531	$	8,568,215

Sales of securities available for sale were as follows:


	Three Months Ended March 31,
	2012			2011
Proceeds from sales	$	9,985,078		$	5,547,541
Gross realized gains		2,137			9
Gross realized losses		(2,628	)		(4	)
Tax (expense) benefit of securities gains/losses		172			(2	)

Trading account securities, at estimated fair value, were as follows:


	March 31,		December 31,
	2012		2011
U.S. Treasury	$	13,409	$	13,609
States and political subdivisions		3,437		—

Total	$	16,846	$	13,609

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


	Three Months Ended March 31,
	2012			2011
Net gain on sales transactions	$	323		$	308
Net mark-to-market gains (losses)		(60	)		—

Net gain on trading account securities	$	263		$	308