Interest-bearing Time Deposits in Banks and Securities (Tables)

3 Months Ended

Mar. 31, 2015

Cash and Cash Equivalents [Abstract]

Summary of Available-for-Sale Securities

A summary of the Company’s available-for-sale securities follows (in thousands):

	March 31, 2015
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
U.S. Treasury securities	$	10,899	$	84	$	—		$	10,983
Obligations of U.S. government sponsored enterprises and agencies		173,777		1,340		—			175,117
Obligations of states and political subdivisions		1,238,354		65,922		(784	)		1,303,492
Corporate bonds and other		95,044		3,089		—			98,133
Residential mortgage-backed securities		900,831		20,752		(1,217	)		920,366
Commercial mortgage-backed securities		179,773		1,575		(109	)		181,239
Total securities available-for-sale	$	2,598,678	$	92,762	$	(2,110	)	$	2,689,330

	December 31, 2014
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
U.S. Treasury securities	$	518	$	2	$	—		$	520
Obligations of U.S. government sponsored enterprises and agencies		128,919		864		(28	)		129,755
Obligations of states and political subdivisions		1,107,795		60,083		(250	)		1,167,628
Corporate bonds and other		95,864		2,894		—			98,758
Residential mortgage-backed securities		871,265		16,804		(2,858	)		885,211
Commercial mortgage-backed securities		134,322		555		(893	)		133,984
Total securities available-for-sale	$	2,338,683	$	81,202	$	(4,029	)	$	2,415,856

Amortized Cost and Estimated Fair Value of Available-for-Sale Securities

The amortized cost and estimated fair value of available-for-sale securities at March 31, 2015, by contractual and expected maturity, are shown below (in thousands):

	Amortized Cost Basis		Estimated Fair Value
Due within one year	$	126,240	$	127,500
Due after one year through five years		725,601		760,706
Due after five years through ten years		657,355		689,777
Due after ten years		8,878		9,742
Mortgage-backed securities		1,080,604		1,101,605
Total	$	2,598,678	$	2,689,330

Continuous Unrealized-Loss Position of Available-for-Sale Securities

The following tables disclose, as of March 31, 2015 and December 31, 2014, the Company’s investment securities that have been in a continuous unrealized-loss position for less than 12 months and for 12 or more months (in thousands):

	Less than 12 Months				12 Months or Longer				Total
March 31, 2015	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of states and political subdivisions	$	84,444	$	748	$	2,570	$	36	$	87,014	$	784
Residential mortgage-backed securities		12,917		13		67,164		1,204		80,081		1,217
Commercial mortgage-backed securities		19,842		57		9,564		52		29,406		109
Total	$	117,203	$	818	$	79,298	$	1,292	$	196,501	$	2,110

	Less than 12 Months				12 Months or Longer				Total
December 31, 2014	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of U.S. government sponsored enterprises and agencies	$	25,480	$	28	$	—	$	—	$	25,480	$	28
Obligations of states and political subdivisions		15,128		60		21,249		190		36,377		250
Residential mortgage-backed securities		76,350		148		128,368		2,710		204,718		2,858
Commercial mortgage-backed securities		48,399		273		55,065		620		103,464		893
Total	$	165,357	$	509	$	204,682	$	3,520	$	370,039	$	4,029