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

12 Months Ended

Dec. 31, 2014

Cash and Cash Equivalents [Abstract]

Summary of Available-for-Sale Securities

A summary of the Company’s available-for-sale securities as of December 31, 2014 and 2013 are as follows (in thousands):

	December 31, 2014
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Securities available-for-sale:
U.S. Treasury securities	$	518	$	2	$	—		$	520
Obligations of U.S. government sponsored enterprises and agencies		128,919		864		(28	)		129,755
Obligations of state 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

	December 31, 2013
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Securities available-for-sale:
Obligations of U.S. government sponsored enterprises and agencies	$	136,416	$	1,672	$	—		$	138,088
Obligations of state and political subdivisions		974,608		27,980		(11,319	)		991,269
Corporate bonds and other		105,490		3,550		—			109,040
Residential mortgage-backed securities		706,289		12,253		(7,922	)		710,620
Commercial mortgage-backed securities		112,323		—		(3,617	)		108,706
Total securities available-for-sale	$	2,035,126	$	45,455	$	(22,858	)	$	2,057,723

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

The amortized cost and estimated fair value of available-for-sale securities at December 31, 2014, by contractual and expected maturity, are shown below (in thousands):

	Amortized Cost Basis		Estimated Fair Value
Due within one year	$	81,336	$	82,078
Due after one year through five years		694,864		726,392
Due after five years through ten years		550,362		580,250
Due after ten years		6,534		7,941
Mortgage-backed securities		1,005,587		1,019,195
Total	$	2,338,683	$	2,415,856

Continuous Unrealized-Loss Position of Available-for-Sale and Held-to-Maturity Securities

The following table discloses, as of December 31, 2014 and 2013, 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
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 state 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

	Less than 12 Months				12 Months or Longer				Total
December 31, 2013	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of state and political subdivisions	$	316,394	$	10,973	$	4,153	$	346	$	320,547	$	11,319
Residential mortgage-backed securities		228,423		7,623		5,624		299		234,047		7,922
Commercial mortgage-backed securities		108,706		3,617		—		—		108,706		3,617
Total	$	653,523	$	22,213	$	9,777	$	645	$	663,300	$	22,858