Investment Securities

6 Months Ended

Jun. 30, 2011

Investment Securities [Abstract]

Investment Securities

(2) Investment Securities

The amortized cost and approximate fair values of investment securities are summarized as follows:

Available-for-Sale			Gross		Gross			Estimated
	Amortized		Unrealized		Unrealized			Fair
June 30, 2011	Cost		Gains		Losses			Value
Obligations of U.S. government agencies	$	1,005,986	$	6,667	$	(25	)	$	1,012,628
U.S. agency residential mortgage-backed securities		828,427		32,176		(230	)		860,373
Private residential mortgage-backed securities		872		10		(19	)		863
Total	$	1,835,285	$	38,853	$	(274	)	$	1,873,864

Held-to-Maturity			Gross		Gross			Estimated
	Amortized		Unrealized		Unrealized			Fair
June 30, 2011	Cost		Gains		Losses			Value
State, county and municipal securities	$	148,674	$	4,780	$	(197	)	$	153,257
Other securities		191		—		—			191
Total	$	148,865	$	4,780	$	(197	)	$	153,448

Available-for-Sale			Gross		Gross			Estimated
	Amortized		Unrealized		Unrealized			Fair
December 31, 2010	Cost		Gains		Losses			Value
Obligations of U.S. government agencies	$	956,017	$	3,337	$	(5,934	)	$	953,420
U.S. agency residential mortgage-backed securities		812,372		24,107		(4,619	)		831,860
Private residential mortgage-backed securities		1,057		10		(12	)		1,055
Total	$	1,769,446	$	27,454	$	(10,565	)	$	1,786,335

Held-to-Maturity			Gross		Gross			Estimated
	Amortized		Unrealized		Unrealized			Fair
December 31, 2010	Cost		Gains		Losses			Value
State, county and municipal securities	$	146,850	$	1,375	$	(1,935	)	$	146,290
Other securities		218		—		—			218
Total	$	147,068	$	1,375	$	(1,935	)	$	146,508

Gross gains of $16 and $15 were realized on the disposition of available-for-sale investment securities during the three months ended June 30, 2011 and 2010, respectively. Gross gains of $18 and $42 were realized on the disposition of available-for-sale investment securities during the six months ended June 30, 2011 and 2010, respectively. No gross losses were realized on the disposition of available-for-sale investment securities during the three and six months ended June 30, 2011 or 2010.

The following table shows the gross unrealized losses and fair values of investment securities, aggregated by investment category, and the length of time individual investment securities have been in a continuous unrealized loss position, as of June 30, 2011 and December 31, 2010.

	Less than 12 Months					12 Months or More					Total
			Gross					Gross					Gross
	Fair		Unrealized			Fair		Unrealized			Fair		Unrealized
June 30, 2011	Value		Losses			Value		Losses			Value		Losses
Available-for-Sale
Obligations of U.S. government agencies	$	53,363	$	(25	)	$	—	$	—		$	53,363	$	(25	)
U.S. agency residential mortgage-backed securities		48,403		(230	)		—		—			48,403		(230	)
Private residential mortgage-backed securities		539		(8	)		205		(11	)		744		(19	)
Total	$	102,305	$	(263	)	$	205	$	(11	)	$	102,510	$	(274	)

	Less than 12 Months					12 Months or More					Total
			Gross					Gross					Gross
	Fair		Unrealized			Fair		Unrealized			Fair		Unrealized
June 30, 2011	Value		Losses			Value		Losses			Value		Losses
Held-to-Maturity
State, county and municipal securities	$	6,503	$	(117	)	$	3,014	$	(80	)	$	9,517	$	(197	)

	Less than 12 Months					12 Months or More					Total
			Gross					Gross					Gross
	Fair		Unrealized			Fair		Unrealized			Fair		Unrealized
December 31, 2010	Value		Losses			Value		Losses			Value		Losses
Available-for-Sale
Obligations of U.S. government agencies	$	498,344	$	(5,934	)	$	—	$	—		$	498,344	$	(5,934	)
U.S. agency residential mortgage-backed securities		160,161		(4,619	)		—		—			160,161		(4,619	)
Private residential mortgage-backed securities		—		—			249		(12	)		249		(12	)
Total	$	658,505	$	(10,553	)	$	249	$	(12	)	$	658,754	$	(10,565	)

	Less than 12 Months					12 Months or More					Total
			Gross					Gross					Gross
	Fair		Unrealized			Fair		Unrealized			Fair		Unrealized
December 31, 2010	Value		Losses			Value		Losses			Value		Losses
Held-to-Maturity
State, county and municipal securities	$	42,178	$	(1,814	)	$	3,023	$	(121	)	$	45,201	$	(1,935	)

The investment portfolio is evaluated quarterly for other-than-temporary declines in the market value of each individual investment security. The Company had 27 and 128 individual investment securities that were in an unrealized loss position as of June 30, 2011 and December 31, 2010, respectively. Unrealized losses as of June 30, 2011 and December 31, 2010 related primarily to fluctuations in the current interest rates. The Company does not have the intent to sell any of the available-for-sale securities in the above table and it is more likely than not that the Company will not be required to sell any such securities before a recovery of cost. No impairment losses were recorded during the three or six months ended June 30, 2011 or 2010.

Maturities of investment securities at June 30, 2011 are shown below. Maturities of mortgage-backed securities have been adjusted to reflect shorter maturities based upon estimated prepayments of principal. All other investment securities maturities are shown at contractual maturity dates.

	Available-for-Sale				Held-to-Maturity
	Amortized		Estimated		Amortized		Estimated
June 30, 2011	Cost		Fair Value		Cost		Fair Value
Within one year	$	309,476	$	316,854	$	6,245	$	5,963
After one year but within five years		1,206,374		1,225,273		23,235		23,769
After five years but within ten years		177,136		183,958		58,708		61,237
After ten years		142,299		147,779		60,486		62,288
Total		1,835,285		1,873,864		148,674		153,257
Investments with no stated maturity		—		—		191		191
Total	$	1,835,285	$	1,873,864	$	148,865	$	153,448