Securities

9 Months Ended

Sep. 30, 2011

Securities [Abstract]

Securities

Note 2 - Securities

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

	September 30, 2011								December 31, 2010
	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	$	247,701	$	31,049	$	—	$	278,750	$	247,421	$	13,517	$	—	$	260,938
Residential mortgage-backed securities		12,081		157		6		12,232		4,405		136		—		4,541
States and political subdivisions		105,485		5,738		—		111,223		30,803		—		1,054		29,749
Other		1,000		—		—		1,000		1,000		—		—		1,000
Total	$	366,267	$	36,944	$	6	$	403,205	$	283,629	$	13,653	$	1,054	$	296,228
Available for Sale:
U. S. Treasury	$	773,362	$	26,553	$	—	$	799,915	$	973,033	$	13,998	$	—	$	987,031
Residential mortgage-backed securities		2,244,650		149,689		1		2,394,338		1,989,299		103,018		987		2,091,330
States and political subdivisions		1,972,996		134,610		39		2,107,567		2,008,618		53,358		21,676		2,040,300
Other		37,992		—		—		37,992		38,809		—		—		38,809
Total	$	5,029,000	$	310,852	$	40	$	5,339,812	$	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 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 and $2.3 billion at September 30, 2011 and December 31, 2010.

As of September 30, 2011, 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
Held to Maturity
Residential mortgage-backed securities	$	6,752	$	6	$	—	$	—	$	6,752	$	6
Total	$	6,752	$	6	$	—	$	—	$	6,752	$	6
Available for Sale
Residential mortgage-backed securities	$	246	$	1	$	—	$	—	$	246	$	1
States and political subdivisions		3,296		31		686		8		3,982		39
Total	$	3,542	$	32	$	686	$	8	$	4,228	$	40

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 September 30, 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 September 30, 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 September 30, 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	$	—	$	—	$	32,816	$	33,229
Due after one year through five years		1,000		1,000		831,398		861,967
Due after five years through ten years		251,039		282,332		174,398		187,265
Due after ten years		102,147		107,641		1,707,746		1,825,021
Residential mortgage-backed securities		12,081		12,232		2,244,650		2,394,338
Equity securities		—		—		37,992		37,992
Total	$	366,267	$	403,205	$	5,029,000	$	5,339,812

Sales of securities available for sale were as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2011		2010		2011		2010
Proceeds from sales	$	39,005	$	—	$	5,587,391	$	9,997,994
Gross realized gains		6,409		—		6,418		8
Gross realized losses		—		—		4		2

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

	September 30,		December 31,
	2011		2010
U.S. Treasury	$	14,035	$	14,986
States and political subdivisions		1,788		115
Total	$	15,823	$	15,101

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

	Three Months Ended September 30,				Nine Months Ended September 30,
	2011		2010		2011		2010
Net gain on sales transactions	$	303	$	509	$	772	$	1,389
Net mark-to-market gains		4		20		11		143
Net gain on trading account securities	$	307	$	529	$	783	$	1,532