Investment Securities (Tables)

3 Months Ended

Mar. 31, 2013

Investments Debt And Equity Securities [Abstract]

Schedule of Amortized Cost and Fair Values of Investment Securities, with Gross Unrealized Gains and Losses

The amortized cost and fair values of investment securities, with gross unrealized gains and losses, consist of the following:

(Dollars in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
March 31, 2013
Securities available for sale:
U.S. Government-sponsored enterprise obligations	$	526,440	$	4,698	$	(298	)	$	530,840
Obligations of state and political subdivisions		117,199		5,826		(179	)		122,846
Mortgage backed securities		1,272,646		25,531		(1,853	)		1,296,324
Other securities		1,460		78		—			1,538
Total securities available for sale	$	1,917,745	$	36,133	$	(2,330	)	$	1,951,548
Securities held to maturity:
U.S. Government-sponsored enterprise obligations	$	69,951	$	1,016	$	—		$	70,967
Obligations of state and political subdivisions		85,723		3,867		(232	)		89,358
Mortgage backed securities		42,768		453		(446	)		42,775
Total securities held to maturity	$	198,442	$	5,336	$	(678	)	$	203,100
December 31, 2012
Securities available for sale:
U.S. Government-sponsored enterprise obligations	$	281,746	$	4,364	$	(386	)	$	285,724
Obligations of state and political subdivisions		120,680		6,573		(178	)		127,075
Mortgage backed securities		1,303,030		29,108		(1,482	)		1,330,656
Other securities		1,460		89		—			1,549
Total securities available for sale	$	1,706,916	$	40,134	$	(2,046	)	$	1,745,004
Securities held to maturity:
U.S. Government-sponsored enterprise obligations	$	69,949	$	1,244	$	—		$	71,193
Obligations of state and political subdivisions		88,909		4,730		(113	)		93,526
Mortgage backed securities		46,204		728		(153	)		46,779
Total securities held to maturity	$	205,062	$	6,702	$	(266	)	$	211,498

Schedule of Securities with Gross Unrealized Losses Aggregated by Investment Category

Information pertaining to securities with gross unrealized losses at March 31, 2013 and December 31, 2012 aggregated by investment category and length of time that individual securities have been in a continuous loss position, follows:

	Less Than Twelve Months					Over Twelve Months					Total
(Dollars in thousands)	Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value
March 31, 2013
Securities available for sale:
U.S. Government-sponsored enterprise obligations	$	(298	)	$	165,763	$	—		$	—	$	(298	)	$	165,763
Obligations of state and political subdivisions		(1	)		336		(178	)		1,094		(179	)		1,430
Mortgage backed securities		(1,851	)		188,106		(2	)		2,679		(1,853	)		190,785
Total securities available for sale	$	(2,150	)	$	354,205	$	(180	)	$	3,773	$	(2,330	)	$	357,978
Securities held to maturity:
U.S. Government-sponsored enterprise obligations	$	—		$	—	$	—		$	—	$	—		$	—
Obligations of state and political subdivisions		(232	)		10,478		—			—		(232	)		10,478
Mortgage backed securities		(446	)		24,372		—			—		(446	)		24,372
Total securities held to maturity	$	(678	)	$	34,850	$	—		$	—	$	(678	)	$	34,850
December 31, 2012
Securities available for sale:
U.S. Government-sponsored enterprise obligations	$	(386	)	$	59,741	$	—		$	—	$	(386	)	$	59,741
Obligations of state and political subdivisions		—			—		(178	)		1,094		(178	)		1,094
Mortgage backed securities		(1,473	)		180,027		(9	)		3,919		(1,482	)		183,946
Total securities available for sale	$	(1,859	)	$	239,768	$	(187	)	$	5,013	$	(2,046	)	$	244,781
Securities held to maturity:
U.S. Government-sponsored enterprise obligations	$	—		$	—	$	—		$	—	$	—		$	—
Obligations of state and political subdivisions		(113	)		8,242		—			—		(113	)		8,242
Mortgage backed securities		(153	)		16,262		—			—		(153	)		16,262
Total securities held to maturity	$	(266	)	$	24,504	$	—		$	—	$	(266	)	$	24,504

Schedule of Amortized Cost and Estimated Fair Value by Maturity of Investment Securities

The amortized cost and estimated fair value by maturity of investment securities at March 31, 2013 are shown in the following table. Securities are classified according to their contractual maturities without consideration of principal amortization, potential prepayments or call options. Accordingly, actual maturities may differ from contractual maturities.

	Securities Available for Sale							Securities Held to Maturity
(Dollars in thousands)	Weighted Average Yield			Amortized Cost		Estimated Fair Value		Weighted Average Yield			Amortized Cost		Estimated Fair Value
Within one year or less		0.12	%	$	78,131	$	78,219		1.77	%	$	21,425	$	21,507
One through five years		1.34			231,579		234,222		2.00			56,171		57,395
After five through ten years		1.90			593,060		606,763		2.53			23,073		24,182
Over ten years		1.75			1,014,975		1,032,344		2.91			97,773		100,016
Totals		1.68	%	$	1,917,745	$	1,951,548		2.48	%	$	198,442	$	203,100

Schedule of Realized Gains and Losses from Sale of Securities Classified as Available for Sale

The following is a summary of realized gains and losses from the sale of securities classified as available for sale.

	Three Months Ended March 31,
(Dollars in thousands)	2013			2012
Realized gains	$	2,365		$	2,815
Realized losses		(37	)		(15	)
Net realized gains	$	2,328		$	2,800

Schedule of Securities in Other Assets on Company's Consolidated Balance Sheets

At March 31, 2013 and December 31, 2012, the Company included the following securities in “Other assets” on the Company’s consolidated balance sheets:

(Dollars in thousands)	March 31, 2013		December 31, 2012
Federal Home Loan Bank (FHLB) stock	$	10,404	$	16,860
Federal Reserve Bank (FRB) stock		28,155		28,155
First National Bankers Bankshares, Inc. (FNBB) stock		899		899
Other investments		406		302
Total equity securities	$	39,864	$	46,216