Investment Securities, Available-for-Sale (Tables)

6 Months Ended

Jun. 30, 2011

Investment Securities, Available-for-Sale [Abstract]

Comparison of amortized cost and estimated fair value of investment securities, available-for-sale

	June 30, 2011
	Weighted			Amortized		Gross Unrealized					Fair
(Dollars in thousands)	Yield			Cost		Gains		Losses			Value
U.S. government and federal agency
Maturing after one year through five years		1.62	%	$	205		5		—			210
U.S. government sponsored enterprises
Maturing after one year through five years		2.31	%		35,245		793		—			36,038
Maturing after five years through ten years		1.89	%		83		—		—			83
		2.31	%		35,328		793		—			36,121
State and local governments and other issues
Maturing within one year		4.10	%		1,147		18		(3	)		1,162
Maturing after one year through five years		2.44	%		100,685		1,205		(1	)		101,889
Maturing after five years through ten years		2.57	%		68,620		1,001		(7	)		69,614
Maturing after ten years		4.88	%		794,825		23,731		(3,630	)		814,926
		4.46	%		965,277		25,955		(3,641	)		987,591
Collateralized debt obligations
Maturing after ten years		8.03	%		8,938		—		(2,985	)		5,953
Residential mortgage-backed securities		2.29	%		1,734,149		22,070		(1,679	)		1,754,540
Total investment securities		3.07	%	$	2,743,897		48,823		(8,305	)		2,784,415

	December 31, 2010
	Weighted			Amortized		Gross Unrealized					Fair
(Dollars in thousands)	Yield			Cost		Gains		Losses			Value
U.S. government and federal agency
Maturing after one year through five years		1.62	%	$	207		4		—			211
U.S. government sponsored enterprises
Maturing after one year through five years		2.38	%		40,715		715		—			41,430
Maturing after five years through ten years		1.94	%		84		—		—			84
Maturing after ten years		0.73	%		4		—		—			4
		2.38	%		40,803		715		—			41,518
State and local governments and other issues
Maturing within one year		4.06	%		1,091		20		(5	)		1,106
Maturing after one year through five years		3.70	%		8,341		214		(10	)		8,545
Maturing after five years through ten years		3.73	%		18,675		379		(56	)		18,998
Maturing after ten years		4.91	%		639,364		5,281		(15,873	)		628,772
		4.86	%		667,471		5,894		(15,944	)		657,421
Collateralized debt obligations
Maturing after ten years		8.03	%		11,178		—		(4,583	)		6,595
Residential mortgage-backed securities		2.23	%		1,675,319		17,569		(2,786	)		1,690,102
Total investment securities		3.00	%	$	2,394,978		24,182		(23,313	)		2,395,847

Gain and loss on sale of investments

	Three Months						Six Months
	ended June 30,						ended June 30,
(Dollars in thousands)	2011			2010			2011			2010
Gross proceeds	$	4,074			23,265			8,208			32,323
Less amortized cost		(4,665	)		(23,023	)		(8,675	)		(31,767	)
Net (loss) gain on sale of investments	$	(591	)		242			(467	)		556
Gross gain on sale of investments	$	39			959			223			1,349
Gross loss on sale of investments		(630	)		(717	)		(690	)		(793	)
Net (loss) gain on sale of investments	$	(591	)		242			(467	)		556

Investments with an unrealized loss position

Investments with an unrealized loss position at June 30, 2011 are summarized as follows:

	Less than 12 Months					12 Months or More					Total
	Fair		Unrealized			Fair		Unrealized			Fair		Unrealized
(Dollars in thousands)	Value		Loss			Value		Loss			Value		Loss
State and local governments and other issues	$	129,535		(2,546	)		13,671		(1,095	)		143,206		(3,641	)
Collateralized debt obligations		—		—			5,953		(2,985	)		5,953		(2,985	)
Residential mortgage-backed securities		164,451		(1,289	)		10,930		(390	)		175,381		(1,679	)
Total temporarily impaired securities	$	293,986		(3,835	)		30,554		(4,470	)		324,540		(8,305	)

Investments with an unrealized loss position at December 31, 2010 are summarized as follows:

	Less than 12 Months					12 Months or More					Total
	Fair		Unrealized			Fair		Unrealized			Fair		Unrealized
(Dollars in thousands)	Value		Loss			Value		Loss			Value		Loss
State and local governments and other issues	$	365,164		(14,680	)		13,122		(1,264	)		378,286		(15,944	)
Collateralized debt obligations		—		—			6,595		(4,583	)		6,595		(4,583	)
Residential mortgage-backed securities		364,925		(1,585	)		19,304		(1,201	)		384,229		(2,786	)
Total temporarily impaired securities	$	730,089		(16,265	)		39,021		(7,048	)		769,110		(23,313	)