Securities (Tables)

9 Months Ended

Sep. 30, 2011

Securities [Abstract]

Summary Of Available-For-Sale And Held-To-Maturity Securities

	September 30, 2011
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Securities available-for-sale:
U. S. Treasury securities	$	15,171	$	253	$	—		$	15,424
Obligations of U.S. government sponsored-enterprises and agencies		244,429		7,092		—			251,521
Obligations of states and political subdivisions		590,453		42,555		(219	)		632,789
Corporate bonds and other		116,006		4,051		(168	)		119,889
Mortgage-backed securities		679,894		29,108		(68	)		708,934
Total securities available-for-sale	$	1,645,953	$	83,059	$	(455	)	$	1,728,557
Securities held-to-maturity:
Obligations of states and political subdivisions	$	3,920	$	45	$	—		$	3,965
Mortgage-backed securities		442		17		—			459
Total securities held-to-maturity	$	4,362	$	62	$	—		$	4,424

	December 31, 2010
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Securities available-for-sale:
U. S. Treasury securities	$	15,253	$	263	$	—		$	15,516
Obligations of U.S. government sponsored-enterprises and agencies		270,706		8,542		—			279,248
Obligations of states and political subdivisions		543,074		12,695		(5,861	)		549,908
Corporate bonds and other		56,710		4,118		—			60,828
Mortgage-backed securities		611,275		22,283		(1,880	)		631,678
Total securities available-for-sale	$	1,497,018	$	47,901	$	(7,741	)	$	1,537,178
Securities held-to-maturity:
Obligations of states and political subdivisions	$	8,549	$	160	$	—		$	8,709
Mortgage-backed securities		515		16		—			531
Total securities held-to-maturity	$	9,064	$	176	$	—		$	9,240

Amortized Cost And Estimated Fair Value Of Debt Securities

	Held-to-Maturity				Available-for-Sale
	Amortized Cost Basis		Estimated Fair Value		Amortized Cost Basis		Estimated Fair Value
Due within one year	$	3,531	$	3,561	$	141,376	$	143,935
Due after one year through five years		389		403		397,698		415,437
Due after five years through ten years		—		—		399,787		431,411
Due after ten years		—		—		27,198		28,840
Mortgage-backed securities		442		460		679,894		708,934
Total	$	4,362	$	4,424	$	1,645,953	$	1,728,557

Continuous Unrealized-Loss Position Of Available-For-Sale And Held-To-Maturity Securities

	$166,507		$166,507		$166,507		$166,507	$166,507		$166,507
	Less than 12 Months			12 Months or Longer				Total
September 30, 2011	Fair Value	Unrealized Loss		Fair Value		Unrealized Loss		Fair Value	Unrealized Loss
Obligations of states and political subdivisions	$5,081	$	219		—		—	$5,081	$	219
Corporate bonds	18,506		168		—		—	18,506		168
Mortgage-backed securities	6,467		68		—		—	6,467		68
Total	$30,054	$	455	$	—	$	—	$30,054	$	455

		$166,507		$166,507		$166,507		$166,507		$166,507		$166,507
	Less than 12 Months				12 Months or Longer				Total
December 31, 2010	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of states and political subdivisions	$	164,437	$	5,665	$	2,070	$	196	$	166,507	$	5,861
Mortgage-backed securities		110,591		1,880		—		—		110,591		1,880
Total	$	275,028	$	7,545	$	2,070	$	196	$	277,098	$	7,741