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

3 Months Ended

Mar. 31, 2016

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, 2016
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
U.S. Treasury securities	$	10,756	$	73	$	—		$	10,829
Obligations of U.S. government sponsored enterprises and agencies		131,484		1,061		—			132,545
Obligations of states and political subdivisions		1,388,369		82,693		(28	)		1,471,034
Corporate bonds and other		68,836		1,896		—			70,732
Residential mortgage-backed securities		793,509		17,180		(963	)		809,726
Commercial mortgage-backed securities		264,231		4,013		(71	)		268,173
Total securities available-for-sale	$	2,657,185	$	106,916	$	(1,062	)	$	2,763,039
	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, 2015
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
U.S. Treasury securities	$	10,792	$	5	$	(2	)	$	10,795
Obligations of U.S. government sponsored enterprises and agencies		148,393		268		(107	)		148,554
Obligations of states and political subdivisions		1,379,879		71,382		(134	)		1,451,127
Corporate bonds and other		86,182		1,778		(5	)		87,955
Residential mortgage-backed securities		781,648		10,993		(3,759	)		788,882
Commercial mortgage-backed securities		247,991		429		(1,834	)		246,586
Total securities available-for-sale	$	2,654,885	$	84,855	$	(5,841	)	$	2,733,899

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, 2016, by contractual and expected maturity, are shown below (in thousands):

	Amortized Cost Basis		Estimated Fair Value
Due within one year	$	168,837	$	170,475
Due after one year through five years		700,497		737,357
Due after five years through ten years		727,661		774,335
Due after ten years		2,450		2,973
Mortgage-backed securities		1,057,740		1,077,899
Total	$	2,657,185	$	2,763,039

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

The following tables disclose, as of March 31, 2016 and 2015, and December 31, 2015, 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, 2016	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of states and political subdivisions	$	6,804	$	23	$	1,071	$	5	$	7,875	$	28
Residential mortgage-backed securities		25,152		357		48,124		606		73,276		963
Commercial mortgage-backed securities		15,553		13		14,520		58		30,073		71
Total	$	47,509	$	393	$	63,715	$	669	$	111,224	$	1,062

	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, 2015	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
U.S. Treasury securities	$	5,110	$	2	$	—	$	—	$	5,110	$	2
Obligations of U.S. government sponsored enterprises and agencies		50,388		107		—		—		50,388		107
Obligations of states and political subdivisions		32,929		127		1,513		7		34,442		134
Corporate bonds and other		7,004		5		—		—		7,004		5
Residential mortgage-backed securities		231,481		1,765		63,919		1,994		295,400		3,759
Commercial mortgage-backed securities		196,163		1,752		9,345		82		205,508		1,834
Total	$	523,075	$	3,758	$	74,777	$	2,083	$	597,852	$	5,841