Securities (Tables)

12 Months Ended

Dec. 31, 2012

Securities

Schedule of amortized cost, unrealized gains and losses and fair values of securities classified available for sale

			Gross		Gross
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
December 31, 2012:	(dollars in thousands)
U.S. Treasury securities	$	103,353	$	1,303	$	—		$	104,656
Obligations of U.S. government corporations and agencies	363,583		6,616		(5		)	370,194
Obligations of states and political subdivisions	274,350		6,176		(238		)	280,288
Residential mortgage-backed securities	210,139		7,576		—			217,715
Corporate debt securities	24,601		139		(26		)	24,714
	976,026		21,810		(269		)	997,567
Mutual funds and other equity securities	2,451		1,479		—			3,930
	$	978,477	$	23,289	$	(269	)	$	1,001,497

			Gross		Gross
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
December 31, 2011:	(dollars in thousands)
U.S. Treasury securities	$	45,550	$	485	$	—		$	46,035
Obligations of U.S. government corporations and agencies	339,983		9,083		(35		)	349,031
Obligations of states and political subdivisions	149,368		5,193		(124		)	154,437
Residential mortgage-backed securities	271,787		6,374		(46		)	278,115
Corporate debt securities	2,532		73		(22		)	2,583
	809,220		21,208		(227		)	830,201
Mutual funds and other equity securities	219		1,329		—			1,548
	$	809,439	$	22,537	$	(227	)	$	831,749

Schedule of amortized cost and fair value of debt securities available for sale by contractual maturity

	Amortized		Fair
	Cost		Value
	(dollars in thousands)
Due in one year or less	$	140,695	$	141,997
Due after one year through five years	548,425		557,505
Due after five years through ten years	217,700		225,070
Due after ten years	69,206		72,995
	$	976,026	$	997,567

Schedule of realized gains and losses related to sales of securities

	For the Years Ended December 31,
	2012			2011			2010
	(dollars in thousands)
Gross security gains	$	1,602		$	174		$	1,025
Gross security (losses)	(5		)	(4		)	(7		)
Net security gains	$	1,597		$	170		$	1,018

Schedule of securities with gross unrealized losses aggregated by investment category and length of time that individual securities have been in continuous loss position

	Continuous unrealized losses  existing for less than 12  months, gross				Continuous unrealized losses  existing greater than 12  months, gross				Total, gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
December 31, 2012:	(dollars in thousands)
Obligations of U.S. government corporations and agencies	$	10,155	$	5	$	—	$	—	$	10,155	$	5
Obligations of states and political subdivisions	37,958		189		3,311		49		41,269		238
Corporate debt securities	15,207		26		—		—		15,207		26
Total temporarily impaired securities	$	63,320	$	220	$	3,311	$	49	$	66,631	$	269

	Continuous unrealized losses  existing for less than 12  months, gross				Continuous unrealized losses  existing greater than 12  months, gross				Total, gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
December 31, 2011:	(dollars in thousands)
Obligations of U.S. government corporations and agencies	$	15,615	$	35	$	—	$	—	$	15,615	$	35
Obligations of states and political subdivisions	21,037		124		—		—		21,037		124
Residential mortgage-backed securities	16,428		46		—		—		16,428		46
Corporate debt securities	455		22						455		22
Total temporarily impaired securities	$	53,535	$	227	$	—	$	—	$	53,535	$	227