Investment Securities

The following tables provide the amortized cost and fair value for the major categories of held-to-maturity and available-for-sale securities. Held-to-maturity securities are carried at amortized cost, which reflects historical cost, adjusted for amortization of premiums and accretion of discounts. Available-for-sale securities are carried at fair value with net unrealized gains or losses reported on an after-tax basis as a component of other comprehensive income in shareholders’ equity.



	March 31, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Securities available for sale
Debt Securities
U.S. government agency debentures	$	35,340	$	115	$	—		$	35,455
U.S. States and political subdivisions	365,543		21,733		(751		)	386,525
Residential mortgage-backed securities:
U.S. government agencies	1,401,241		53,388		(213		)	1,454,416
Commercial mortgage-backed securities:
U.S. government agencies	27,689		34		(60		)	27,663
Residential collateralized mortgage-backed securities:
U.S. government agencies	1,226,260		25,046		(2		)	1,251,304
Non-agency	41,741		91		—			41,832
Commercial collateralized mortgage-backed securities:
U.S. government agencies	147,214		675		(534		)	147,355
Corporate debt securities	158,019		955		(15,185		)	143,789
Total debt securities	3,403,047		102,037		(16,745		)	3,488,339
Marketable equity securities	3,308		—		—			3,308
Total securities available for sale	$	3,406,355	$	102,037	$	(16,745	)	$	3,491,647
Securities held to maturity
Debt Securities
U.S. States and political subdivisions	$	100,840	$	3,025	$	—		$	103,865
Total securities held to maturity	$	100,840	$	3,025	$	—		$	103,865



	December 31, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Securities available for sale
Debt Securities
U.S. government agency debentures	$	122,711	$	358	$	—		$	123,069
U.S. States and political subdivisions	334,916		22,865		(50		)	357,731
Residential mortgage-backed securities:
U.S. government agencies	1,407,345		53,129		(131		)	1,460,343
Residential collateralized mortgage-backed securities:
U.S. government agencies	1,115,832		22,058		(55		)	1,137,835
Non-agency	43,225		82		—			43,307
Commercial collateralized mortgage-backed securities:
U.S. government agencies	127,624		1,648		(145		)	129,127
Corporate debt securities	115,947		276		(17,381		)	98,842
Total debt securities	3,267,600		100,416		(17,762		)	3,350,254
Marketable equity securities	3,299		—		—			3,299
Total securities available for sale	$	3,270,899	$	100,416	$	(17,762	)	$	3,353,553
Securities held to maturity
Debt Securities
U.S. States and political subdivisions	$	82,764	$	2,348	$	—		$	85,112
Total securities held to maturity	$	82,764	$	2,348	$	—		$	85,112



	March 31, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Securities available for sale
Debt Securities
U.S. government agency debentures	$	409,090	$	549	$	(248	)	$	409,391
U.S. States and political subdivisions	292,531		5,468		(1,271		)	296,728
Residential mortgage-backed securities:
U.S. government agencies	1,464,666		49,591		(1,737		)	1,512,520
Residential collateralized mortgage-backed securities:
U.S. government agencies	999,719		16,194		(2,557		)	1,013,356
Non-agency	77,517		97		(5		)	77,609
Corporate debt securities	61,448		—		(12,140		)	49,308
Total debt securities	3,304,971		71,899		(17,958		)	3,358,912
Marketable equity securities	3,839		—		—			3,839
Total securities available for sale	$	3,308,810	$	71,899	$	(17,958	)	$	3,362,751
Securities held to maturity
Debt Securities
U.S. States and political subdivisions	$	65,923	$	1,980	$	—		$	67,903
Total securities held to maturity	$	65,923	$	1,980	$	—		$	67,903

Federal Reserve Bank (“FRB”) and Federal Home Loan Bank (“FHLB”) stock constitute the majority of other investments on the consolidated balance sheets.



	March 31, 2012		December 31, 2011		March 31, 2011
FRB stock	$	21,003	$	21,003	$	20,804
FHLB stock	119,145		119,145		139,398
Other	565		578		616
Total other investments	$	140,713	$	140,726	$	160,818

FRB and FHLB stock is classified as a restricted investment, carried at cost and valued based on the ultimate recoverability of par value. Cash and stock dividends received on the stock are reported as interest income. There are no identified events or changes in circumstances that may have a significant adverse effect on these investments carried at cost.

Securities with a carrying value of $1.9 billion, $1.9 billion and $2.2 billion as of March 31, 2012, December 31, 2011 and March 31, 2011, respectively, were pledged to secure trust and public deposits and securities sold under agreements to repurchase and for other purposes required or permitted by law.

Gross Unrealized Losses and Fair Value

The following table presents the gross unrealized losses and fair value of securities in the securities available-for-sale portfolio by length of time that individual securities in each category had been in a continuous loss position.



	March 31, 2012
	Less than 12 months						12 months or longer						Total
	Fair Value		Unrealized Losses			Number of Impaired Securities	Fair Value		Unrealized Losses			Number of Impaired Securities	Fair Value		Unrealized Losses
Debt Securities
U.S. government agency debentures	$	—	$	—		—	$	—	$	—		—	$	—	$	—
U.S. States and political subdivisions	26,915		(751		)	39	—		—			—	26,915		(751		)
Residential mortgage-backed securities:
U.S. government agencies	40,036		(213		)	4	—		—			—	40,036		(213		)
Commercial mortgage-backed securities:
U.S. government agencies	12,329		(60		)	2	—		—			—	12,329		(60		)
Residential collateralized mortgage-backed securities:
U.S. government agencies	4,322		(2		)	1	—		—			—	4,322		(2		)
U.S. non agencies	—		—			—	2		—			1	2		—
Commercial collateralized mortgage-backed securities:
U.S. government agencies	64,435		(534		)	6	—		—			—	64,435		(534		)
Corporate debt securities	33,250		(342		)	12	46,657		(14,843		)	8	79,907		(15,185		)
Total temporarily impaired securities	$	181,287	$	(1,902	)	64	$	46,659	$	(14,843	)	9	$	227,946	$	(16,745	)



	December 31, 2011
	Less than 12 months						12 months or longer						Total
	Fair Value		Unrealized Losses			Number of Impaired Securities	Fair Value		Unrealized Losses			Number of Impaired Securities	Fair Value		Unrealized Losses
Debt Securities
U.S. States and political subdivisions	$	5,249	$	(50	)	6	$	—	$	—		—	$	5,249	$	(50	)
Residential mortgage-backed securities:
U.S. government agencies	40,020		(129		)	4	149		(2		)	1	40,169		(131		)
Residential collateralized mortgage-backed securities:
U.S. government agencies	58,337		(102		)	7	—		—			—	58,337		(102		)
Non-agency	—		—			—	2		—			1	2		—
Commercial collateralized mortgage-backed securities:
U.S. government agencies	19,892		(98		)	1	—		—			—	19,892		(98		)
Corporate debt securities	24,846		(127		)	8	44,234		(17,254		)	8	69,080		(17,381		)
Total temporarily impaired securities	$	148,344	$	(506	)	26	$	44,385	$	(17,256	)	10	$	192,729	$	(17,762	)



	March 31, 2011
	Less than 12 months						12 months or longer						Total
	Fair Value		Unrealized Losses			Number of Impaired Securities	Fair Value		Unrealized Losses			Number of Impaired Securities	Fair Value		Unrealized Losses
Debt Securities
U.S. government agency debentures	$	153,756	$	(248	)	11	$	—	$	—		—	$	153,756	$	(248	)
U.S. States and political subdivisions	55,412		(1,248		)	94	660		(23		)	1	56,072		(1,271		)
Residential mortgage-backed securities:
U.S. government agencies	243,316		(1,734		)	20	173		(3		)	1	243,489		(1,737		)
Residential collateralized mortgage-backed securities:
U.S. government agencies	387,309		(2,562		)	26	—		—			—	387,309		(2,562		)
Corporate debt securities	—		—			—	49,308		(12,140		)	8	49,308		(12,140		)
Total temporarily impaired securities	$	839,793	$	(5,792	)	151	$	50,141	$	(12,166	)	10	$	889,934	$	(17,958	)

At least quarterly the Corporation conducts a comprehensive security-level impairment assessment on all securities in an unrealized loss position to determine if other-than-temporary impairment (“OTTI”) exists. An unrealized loss exists when the current fair value of an individual security is less than its amortized cost basis. Under the current OTTI accounting model for debt securities, an OTTI loss must be recognized for a debt security in an unrealized loss position if the Corporation intends to sell the security or it is more likely than not that the Corporation will be required to sell the security before recovery of its amortized cost basis. In this situation, the amount of loss recognized in income is equal to the difference between the fair value and the amortized cost basis of the security. Even if the Corporation does not expect to sell the security, the Corporation must evaluate the expected cash flows to be received to determine if a credit loss has occurred. In the event of a credit loss, only the amount of impairment associated with the credit loss is recognized in income. The portion of the unrealized loss relating to other factors, such as liquidity conditions in the market or changes in market interest rates, is recorded in other comprehensive income. Equity securities are also evaluated to determine whether the unrealized loss is expected to be recoverable based on whether evidence exists to support a realizable value equal to or greater than the amortized cost basis. If it is probable that the Corporation will not recover the amortized cost basis, taking into consideration the estimated recovery period and its ability to hold the equity security until recovery, OTTI is recognized.

The security-level assessment is performed on each security, regardless of the classification of the security as available for sale or held to maturity. The assessments are based on the nature of the securities, the financial condition of the issuer, the extent and duration of the securities, the extent and duration of the loss and whether Management intends to sell or it is more likely than not that it will be required to sell a security before recovery of its amortized cost basis, which may be maturity. For those securities for which the assessment shows the Corporation will recover the entire cost basis, Management does not intend to sell these securities and it is not more likely than not that the Corporation will be required to sell them before the anticipated recovery of the amortized cost basis, the gross unrealized losses are recognized in other comprehensive income, net of tax.

As of March 31, 2012, gross unrealized losses are concentrated within corporate debt securities which is composed of eight, single issuer, trust preferred securities with stated maturities. Such investments are less than 2%0% of the fair value of the entire investment portfolio. None of the corporate issuers have deferred paying dividends on their issued trust preferred shares in which the Corporation is invested. The fair values of these investments have been impacted by market conditions which have caused risk premiums to increase, resulting in the decline in the fair value of the trust preferred securities. Management believes the Corporation will fully recover the cost of these securities and it does not intend to sell these securities and it is not more likely than not that it will be required to sell them before the anticipated recovery of the remaining amortized cost basis, which may be maturity. As a result, Management concluded that these securities were not OTTI at March 31, 2012 and has recognized the total amount of the impairment in other comprehensive income, net of tax.

Realized Gains and Losses

The following table shows the proceeds from sales of available-for-sale securities and the gross realized gains and losses on those sales that have been included in earnings. Gains or losses on the sales of available-for-sale securities are recognized upon sale and are determined using the specific identification method.



	Quarter ended March 31,
	2012		2011
Proceeds	$	94,865	$	—
Realized gains	260		—
Realized losses	—		—
Net securities gains	$	260	$	—

Contractual Maturity of Debt Securities

The following table shows the remaining contractual maturities and contractual yields of debt securities held-to-maturity and available-for-sale as of March 31, 2012. Estimated lives on mortgage-backed securities may differ from contractual maturities as issuers may have the right to call or prepay obligations with or without call or prepayment penalties.



	U.S. Government agency debentures			U.S. States and political subdivisions obligations			Residential mortgage-backed securities - U.S govt. agency obligations			Commercial mortgage-backed securities - U.S govt. agency obligations			Residential collateralized mortgage obligations - U.S. govt. agency obligations			Residential collateralized mortgage obligations - non - U.S. govt. agency issued			Commercial collateralized mortgage obligations - U.S. govt. agency obligations			Corporate debt securities			Total			Weighted Average Yield
Securities Available for Sale
Remaining maturity:
One year or less	$	35,455		$	8,808		$	4,408		$	—		$	51,403		$	—		$	—		$	—		$	100,074		2.98	%
Over one year through five years	—			25,781			1,291,288			5,067			1,174,567			41,832			54,273			23,976			2,616,784			2.75	%
Over five years through ten years	—			186,676			158,720			22,596			25,334			—			93,082			73,156			559,564			3.34	%
Over ten years	—			165,260			—			—			—			—			—			46,657			211,917			41.60	%
Fair Value	$	35,455		$	386,525		$	1,454,416		$	27,663		$	1,251,304		$	41,832		$	147,355		$	143,789		$	3,488,339		2.94	%
Amortized Cost	$	35,340		$	365,543		$	1,401,241		$	27,689		$	1,226,260		$	41,741		$	147,214		$	158,019		$	3,403,047
Weighted-Average Yield	0.73		%	5.39		%	3.10		%	0.59		%	2.43		%	0.52		%	2.47		%	1.85		%	2.94		%
Weighted-Average Maturity	0.65			10.21			3.60			5.98			3.36			2.35			6.02			9.60			4.58
Securities Held to Maturity
Remaining maturity:
One year or less	$	—		$	40,713		$	—		$	—		$	—		$	—		$	—		$	—		$	40,713		1.53	%
Over one year through five years	—			15,098			—			—			—			—			—			—			15,098			4.52	%
Over five years through ten years	—			5,204			—			—			—			—			—			—			5,204			5.46	%
Over ten years	—			42,850			—			—			—			—			—			—			42,850			7.16	%
Fair Value	$	—		$	103,865		$	—		$	—		$	—		$	—		$	—		$	—		$	103,865		4.49	%
Amortized Cost	$	—		$	100,840		$	—		$	—		$	—		$	—		$	—		$	—		$	100,840
Weighted-Average Yield	—		%	4.49		%	—		%	—		%	—		%	—		%	—		%	—		%	4.49		%
Weighted-Average Maturity	—			6.42			—			—			—			—			—			—			6.42