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

6 Months Ended

Jun. 30, 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):

	June 30, 2016
			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost Basis		Holding Gains		Holding Losses			Fair Value
U.S. Treasury securities	$	10,721	$	90	$	—		$	10,811
Obligations of U.S. government sponsored enterprises and agencies		121,174		1,178		—			122,352
Obligations of states and political subdivisions		1,418,342		97,980		(10	)		1,516,312
Corporate bonds and other		71,687		1,723		—			73,410
Residential mortgage-backed securities		787,451		18,928		(606	)		805,773
Commercial mortgage-backed securities		261,662		5,068		(32	)		266,698
Total securities available-for-sale	$	2,671,037	$	124,967	$	(648	)	$	2,795,356

	June 30, 2015
			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost Basis		Holding Gains		Holding Losses			Fair Value
U.S. Treasury securities	$	10,864	$	72	$	—		$	10,936
Obligations of U.S. government sponsored enterprises and agencies		164,351		985		—			165,336
Obligations of states and political subdivisions		1,340,163		49,483		(5,400	)		1,384,246
Corporate bonds and other		94,485		2,623		—			97,108
Residential mortgage-backed securities		856,546		14,383		(2,838	)		868,091
Commercial mortgage-backed securities		203,482		591		(677	)		203,396
Total securities available-for-sale	$	2,669,891	$	68,137	$	(8,915	)	$	2,729,113
	December 31, 2015
			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost Basis		Holding Gains		Holding Losses			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 June 30, 2016, by contractual and expected maturity, are shown below (in thousands):

	Amortized		Estimated
	Cost Basis		Fair Value
Due within one year	$	180,342	$	182,079
Due after one year through five years		669,211		705,585
Due after five years through ten years		762,452		824,643
Due after ten years		9,919		10,578
Mortgage-backed securities		1,049,113		1,072,471
Total	$	2,671,037	$	2,795,356

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

The following tables disclose, as of June 30, 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
June 30, 2016	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of states and political subdivisions	$	5,959	$	7	$	745	$	3	$	6,704	$	10
Residential mortgage-backed securities		16,085		14		60,360		592		76,445		606
Commercial mortgage-backed securities		—		—		14,152		32		14,152		32
Total	$	22,044	$	21	$	75,257	$	627	$	97,301	$	648
	Less than 12 Months				12 Months or Longer				Total
June 30, 2015	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of states and political subdivisions	$	304,510	$	5,335	$	2,531	$	65	$	307,041	$	5,400
Residential mortgage-backed securities		176,569		844		65,562		1,994		242,131		2,838
Commercial mortgage-backed securities		134,151		628		9,504		49		143,655		677
Total	$	615,230	$	6,807	$	77,597	$	2,108	$	692,827	$	8,915
	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