Securities (Tables)

6 Months Ended

Jun. 30, 2016

Securities Available for Sale

This table provides detailed information about securities available for sale at June 30, 2016 and December 31, 2015 (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
June 30, 2016
U.S. Treasury	$	362,766	$	576	$	(5	)	$	363,337
U.S. Agencies		421,149		507		(31	)		421,625
Mortgage-backed		3,553,661		53,444		(6,930	)		3,600,175
State and political subdivisions		2,257,535		48,687		(243	)		2,305,979
Corporates		80,044		85		(66	)		80,063
Total	$	6,675,155	$	103,299	$	(7,275	)	$	6,771,179
			Gross		Gross
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
December 31, 2015
U.S. Treasury	$	350,354	$	1	$	(576	)	$	349,779
U.S. Agencies		667,414		7		(1,032	)		666,389
Mortgage-backed		3,598,115		12,420		(38,089	)		3,572,446
State and political subdivisions		2,116,543		23,965		(2,095	)		2,138,413
Corporates		80,585		—		(663	)		79,922
Total	$	6,813,011	$	36,393	$	(42,455	)	$	6,806,949

Gross Unrealized Losses and Fair Value of Investment Securities Available for Sale

The following table shows the Company’s available for sale investments’ gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at June 30, 2016 and December 31, 2015 (in thousands):

June 30, 2016	Less than 12 months					12 months or more					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Description of Securities
U.S. Treasury	$	5,025	$	(5	)	$	—	$	—		$	5,025	$	(5	)
U.S. Agencies		45,635		(24	)		3,036		(7	)		48,671		(31	)
Mortgage-backed		204,221		(744	)		312,994		(6,186	)		517,215		(6,930	)
State and political subdivisions		131,455		(188	)		10,155		(55	)		141,610		(243	)
Corporates		8,748		(2	)		39,069		(64	)		47,817		(66	)
Total temporarily-impaired debt securities available for sale	$	395,084	$	(963	)	$	365,254	$	(6,312	)	$	760,338	$	(7,275	)

December 31, 2015	Less than 12 months					12 months or more					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Description of Securities
U.S. Treasury	$	344,556	$	(576	)	$	—	$	—		$	344,556	$	(576	)
U.S. Agencies		615,993		(1,032	)		—		—			615,993		(1,032	)
Mortgage-backed		2,056,316		(21,013	)		426,959		(17,076	)		2,483,275		(38,089	)
State and political subdivisions		479,197		(1,316	)		60,324		(779	)		539,521		(2,095	)
Corporates		29,126		(183	)		50,796		(480	)		79,922		(663	)
Total temporarily-impaired debt securities available for sale	$	3,525,188	$	(24,120	)	$	538,079	$	(18,335	)	$	4,063,267	$	(42,455	)

Securities Held to Maturity

The table below provides detailed information for securities held to maturity at June 30, 2016 and December 31, 2015 (in thousands):

			Net
	Amortized		Unrealized		Fair
	Cost		Gains		Value
June 30, 2016
State and political subdivisions	$	880,600	$	111,115	$	991,715
December 31, 2015
State and political subdivisions	$	667,106	$	24,273	$	691,379

Schedule of Federal Reserve Bank Stock and Federal Home Loan Bank Stock and Other Securities

The table below provides detailed information for Federal Reserve Bank (FRB) stock and Federal Home Loan Bank (FHLB) stock and other securities at June 30, 2016 and December 31, 2015 (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
June 30, 2016
FRB and FHLB stock	$	33,667	$	—	$	—		$	33,667
Other securities – marketable		4		7,951		—			7,955
Other securities – non-marketable		23,974		730		(26	)		24,678
Total Other securities	$	57,645	$	8,681	$	(26	)	$	66,300
December 31, 2015
FRB and FHLB stock	$	33,215	$	—	$	—		$	33,215
Other securities – marketable		5		7,159		—			7,164
Other securities – non-marketable		23,855		964		—			24,819
Total Other securities	$	57,075	$	8,123	$	—		$	65,198

Available-for-sale Securities [Member]

Contractual Maturity Information

The following table presents contractual maturity information for securities available for sale at June 30, 2016 (in thousands):

	Amortized		Fair
	Cost		Value
Due in 1 year or less	$	931,783	$	932,836
Due after 1 year through 5 years		1,118,929		1,136,979
Due after 5 years through 10 years		861,965		887,760
Due after 10 years		208,817		213,429
Total		3,121,494		3,171,004
Mortgage-backed securities		3,553,661		3,600,175
Total securities available for sale	$	6,675,155	$	6,771,179

Held-to-maturity Securities [Member]

Contractual Maturity Information

The following table presents contractual maturity information for securities held to maturity at June 30, 2016 (in thousands):

	Amortized		Fair
	Cost		Value
Due in 1 year or less	$	16,268	$	18,321
Due after 1 year through 5 years		76,310		85,939
Due after 5 years through 10 years		481,148		541,859
Due after 10 years		306,874		345,596
Total securities held to maturity	$	880,600	$	991,715