Investment Securities (Tables)

9 Months Ended

Sep. 30, 2011

Investments, Debt and Equity Securities [Abstract]

Schedule of Amortized Cost and Fair Values of Investment Securities

The following tables present the amortized cost and estimated fair values of investment securities:

Held to Maturity at September 30, 2011	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
U.S. Government sponsored agency securities	$	5,987	$	—	$	(7	)	$	5,980
State and municipal securities	179		—		—			179
Mortgage-backed securities	568		47		—			615
	$	6,734	$	47	$	(7	)	$	6,774
Available for Sale at September 30, 2011
Equity securities	$	123,483	$	2,291	$	(5,408	)	$	120,366
U.S. Government securities	1,325		—		—			1,325
U.S. Government sponsored agency securities	4,735		110		(1		)	4,844
State and municipal securities	320,969		13,091		—			334,060
Corporate debt securities	130,455		4,892		(12,912		)	122,435
Collateralized mortgage obligations	1,078,396		29,212		(353		)	1,107,255
Mortgage-backed securities	802,142		36,763		(69		)	838,836
Auction rate securities	255,472		283		(15,053		)	240,702
	$	2,716,977	$	86,642	$	(33,796	)	$	2,769,823

Held to Maturity at December 31, 2010	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
U.S. Government sponsored agency securities	$	6,339	$	—	$	(1	)	$	6,338
State and municipal securities	346		—		—			346
Mortgage-backed securities	1,066		68		—			1,134
	$	7,751	$	68	$	(1	)	$	7,818
Available for Sale at December 31, 2010
Equity securities	$	133,570	$	3,872	$	(974	)	$	136,468
U.S. Government securities	1,649		—		—			1,649
U.S. Government sponsored agency securities	4,888		172		(2		)	5,058
State and municipal securities	345,053		6,003		(1,493		)	349,563
Corporate debt securities	137,101		3,808		(16,123		)	124,786
Collateralized mortgage obligations	1,085,613		23,457		(5,012		)	1,104,058
Mortgage-backed securities	843,446		31,080		(3,054		)	871,472
Auction rate securities	271,645		892		(11,858		)	260,679
	$	2,822,965	$	69,284	$	(38,516	)	$	2,853,733

Schedule of Amortized Cost and Fair Values of Debt Securities by Contractual Maturities

The amortized cost and estimated fair values of debt securities as of September 30, 2011, by contractual maturity, are shown in the following table. Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

	Held to Maturity				Available for Sale
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(in thousands)
Due in one year or less	$	6,052	$	6,045	$	70,852	$	71,305
Due from one year to five years	114		114		46,088		47,500
Due from five years to ten years	—		—		127,391		135,592
Due after ten years	—		—		468,625		448,969
	6,166		6,159		712,956		703,366
Collateralized mortgage obligations	—		—		1,078,396		1,107,255
Mortgage-backed securities	568		615		802,142		838,836
	$	6,734	$	6,774	$	2,593,494	$	2,649,457

Summary of Gains and Losses from Equity and Debt Securities, and Losses Recognized from Other-than-Temporary Impairment

The following table presents information related to the Corporation’s gains and losses on the sales of equity and debt securities, and losses recognized for the other-than-temporary impairment of investments:

	Gross Realized Gains		Gross Realized Losses			Other-than- temporary Impairment Losses			Net Gains (Losses)
	(in thousands)
Three months ended September 30, 2011
Equity securities	$	146	$	—		$	(244	)	$	(98	)
Debt securities	—		—			(345		)	(345		)
Total	$	146	$	—		$	(589	)	$	(443	)
Three months ended September 30, 2010:
Equity securities	$	601	$	(391	)	$	(480	)	$	(270	)
Debt securities	4,485		(54		)	(2,335		)	2,096
Total	$	5,086	$	(445	)	$	(2,815	)	$	1,826
Nine months ended September 30, 2011
Equity securities	$	194	$	—		$	(575	)	$	(381	)
Debt securities	3,605		(19		)	(1,698		)	1,888
Total	$	3,799	$	(19	)	$	(2,273	)	$	1,507
Nine months ended September 30, 2010:
Equity securities	$	1,451	$	(391	)	$	(1,813	)	$	(753	)
Debt securities	10,809		(72		)	(9,477		)	1,260
Total	$	12,260	$	(463	)	$	(11,290	)	$	507

Summary of Cumulative Other-than-Temporary Impairment Charges Recognized in Earnings for Pooled Trust Preferred Securities Held

The following table presents a summary of the cumulative credit related other-than-temporary impairment charges, recognized as components of earnings, for debt securities still held by the Corporation:

	Three Months Ended September 30						Nine Months Ended September 30
	2011			2010			2011			2010
	(in thousands)
Balance of cumulative credit losses on debt securities, beginning of period	$	(28,876	)	$	(22,754	)	$	(27,560	)	$	(15,612	)
Additions for credit losses recorded which were not previously recognized as components of earnings	(345		)	(2,335		)	(1,698		)	(9,477		)
Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	40			21			77			21
Balance of cumulative credit losses on debt securities, end of period	$	(29,181	)	$	(25,068	)	$	(29,181	)	$	(25,068	)

Gross Unrealized Losses and Fair Values of Investments by Category and Length of Time in Continuous Unrealized Loss Position

The following table presents the gross unrealized losses and estimated fair values of investments, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at September 30, 2011:

	Less than 12 months					12 months or longer					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
	(in thousands)
U.S. Government sponsored agency securities	$	5,401	$	(7	)	$	175	$	(1	)	$	5,576	$	(8	)
Corporate debt securities	16,909		(1,060		)	41,371		(11,852		)	58,280		(12,912		)
Collateralized mortgage obligations	101,324		(353		)	—		—			101,324		(353		)
Mortgage-backed securities	26,100		(69		)	—		—			26,100		(69		)
Auction rate securities	37,059		(1,915		)	182,341		(13,138		)	219,400		(15,053		)
Total debt securities	186,793		(3,404		)	223,887		(24,991		)	410,680		(28,395		)
Equity securities	13,747		(4,951		)	1,316		(457		)	15,063		(5,408		)
	$	200,540	$	(8,355	)	$	225,203	$	(25,448	)	$	425,743	$	(33,803	)

Summary of Amortized Cost and Fair Values of Corporate Debt Securities

The following table presents the amortized cost and estimated fair values of corporate debt securities:

	September 30, 2011				December 31, 2010
	Amortized cost		Estimated fair value		Amortized cost		Estimated fair value
	(in thousands)
Single-issuer trust preferred securities	$	86,366	$	77,861	$	91,257	$	81,789
Subordinated debt	35,080		36,754		34,995		35,915
Pooled trust preferred securities	6,464		5,275		8,295		4,528
Corporate debt securities issued by financial institutions	127,910		119,890		134,547		122,232
Other corporate debt securities	2,545		2,545		2,554		2,554
Available for sale corporate debt securities	$	130,455	$	122,435	$	137,101	$	124,786