5. Securities

Securities Available for Sale

This table provides detailed information about securities available for sale at September 30, 2015 and December 31, 2014 (in thousands):


September 30, 2015	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury	$	351,767	$	801	$	—		$	352,568
U.S. Agencies		711,381		1,188		(86	)		712,483
Mortgage-backed		3,395,612		34,135		(14,172	)		3,415,575
State and political subdivisions		2,089,507		24,257		(3,080	)		2,110,684
Corporates		80,853		45		(463	)		80,435

Total	$	6,629,120	$	60,426	$	(17,801	)	$	6,671,745


December 31, 2014	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury	$	519,484	$	501	$	(525	)	$	519,460
U.S. Agencies		991,084		780		(1,175	)		990,689
Mortgage-backed		3,276,009		28,470		(26,875	)		3,277,604
State and political subdivisions		1,983,549		22,973		(5,165	)		2,001,357
Corporates		124,096		—		(1,270	)		122,826

Total	$	6,894,222	$	52,724	$	(35,010	)	$	6,911,936

The following table presents contractual maturity information for securities available for sale at September 30, 2015 (in thousands):


	Amortized		Fair
	Cost		Value
Due in 1 year or less	$	806,162	$	807,367
Due after 1 year through 5 years		1,519,825		1,532,670
Due after 5 years through 10 years		846,257		855,142
Due after 10 years		61,264		60,991

Total		3,233,508		3,256,170
Mortgage-backed securities		3,395,612		3,415,575

Total securities available for sale	$	6,629,120	$	6,671,745

Securities may be disposed of before contractual maturities due to sales by the Company or because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

For the nine months ended September 30, 2015, proceeds from the sales of securities available for sale were $782.8 million compared to $410.6 million for the same period in 2014. Securities transactions resulted in gross realized gains of $8.5 million and $4.1 million for the nine months ended September 30, 2015 and 2014, respectively. The gross realized losses for the nine months ended September 30, 2015 and 2014 were $48 thousand and $11 thousand, respectively.

Securities available for sale with a market value of $5.3 billion at September 30, 2015 and $5.7 billion at December 31, 2014 were pledged to secure U.S. Government deposits, other public deposits, certain trust deposits, and sales of securities with simultaneous agreements to repurchase the securities at specified maturities (repurchase agreements). Of this amount, securities with a market value of $1.7 billion at September 30, 2015 and $1.2 billion at December 31, 2014 were pledged at the Federal Reserve Discount Window but were unencumbered as of those dates.

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 September 30, 2015 and December 31, 2014 (in thousands):


September 30, 2015	Less than 12 months					12 months or more					Total
Description of Securities	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury	$	—	$	—		$	—	$	—		$	—	$	—
U.S. Agencies		72,409		(41	)		36,955		(45	)		109,364		(86	)
Mortgage-backed		621,731		(5,216	)		383,140		(8,956	)		1,004,871		(14,172	)
State and political subdivisions		331,467		(1,897	)		69,275		(1,183	)		400,742		(3,080	)
Corporates		15,764		(51	)		50,959		(412	)		66,723		(463	)

Total temporarily-impaired debt securities available for sale	$	1,041,371	$	(7,205	)	$	540,329	$	(10,596	)	$	1,581,700	$	(17,801	)


December 31, 2014	Less than 12 months					12 months or more					Total
Description of Securities	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury	$	236,591	$	(329	)	$	14,863	$	(196	)	$	251,454	$	(525	)
U.S. Agencies		387,999		(689	)		81,593		(486	)		469,592		(1,175	)
Mortgage-backed		727,142		(8,370	)		616,044		(18,504	)		1,343,186		(26,874	)
State and political subdivisions		401,934		(1,406	)		226,678		(3,760	)		628,612		(5,166	)
Corporates		36,655		(243	)		86,171		(1,027	)		122,826		(1,270	)

Total temporarily-impaired debt securities available for sale	$	1,790,321	$	(11,037	)	$	1,025,349	$	(23,973	)	$	2,815,670	$	(35,010	)

The unrealized losses in the Company’s investments in U.S. treasury obligations, U.S. government agencies, Government Sponsored Entity (GSE) mortgage-backed securities, municipal securities, and corporates were caused by changes in interest rates. The Company does not have the intent to sell these securities and does not believe it is more likely than not that the Company will be required to sell these securities before a recovery of amortized cost. The Company expects to recover its cost basis in the securities and does not consider these investments to be other-than-temporarily impaired at September 30, 2015.

Securities Held to Maturity

The table below provides detailed information for securities held to maturity at September 30, 2015 and December 31, 2014 (in thousands):


September 30, 2015	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
State and political subdivisions	$	588,478	$	22,904	$	—	$	611,382


December 31, 2014
State and political subdivisions	$	278,054	$	26,058	$	—	$	304,112

The following table presents contractual maturity information for securities held to maturity at September 30, 2015 (in thousands):


	Amortized Cost		Fair Value
Due in 1 year or less	$	4,366	$	4,536
Due after 1 year through 5 years		89,100		92,568
Due after 5 years through 10 years		339,631		352,850
Due after 10 years		155,381		161,428

Total securities held to maturity	$	588,478	$	611,382

Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

There were no sales of securities held to maturity during the first nine months of 2015 or 2014.

Trading Securities

The net unrealized gains on trading securities at September 30, 2015 and September 30, 2014 were $8 thousand and $39 thousand, respectively, and were included in trading and investment banking income on the Consolidated Statements of Income.

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 September 30, 2015 and December 31, 2014 (in thousands):


			Gross		Gross
	Amortized		Unrealized		Unrealized			Fair
September 30, 2015	Cost		Gains		Losses			Value
FRB and FHLB stock	$	34,006	$	—	$	—		$	34,006
Other securities – marketable		—		12,006		—			12,006
Other securities – non-marketable		20,867		1,571		(79	)		22,359

Total Federal Reserve Bank stock and other	$	54,873	$	13,577	$	(79	)	$	68,371


December 31, 2014
FRB and FHLB stock	$	26,279	$	—	$	—		$	26,279
Other securities – marketable		—		16,668		—			16,668
Other securities – non-marketable		21,669		3,937		(79	)		25,527

Total Federal Reserve Bank stock and other	$	47,948	$	20,605	$	(79	)	$	68,474

Investment in FRB stock is based on the capital structure of the investing bank, and investment in FHLB stock is mainly tied to the level of borrowings from the FHLB. These holdings are carried at cost. Other marketable and non-marketable securities include Prairie Capital Management (PCM) alternative investments in hedge funds and private equity funds, which are accounted for as equity-method investments. The fair value of other marketable securities includes alternative investment securities of $12.0 million at September 30, 2015 and $16.7 million at December 31, 2014. The fair value of other non-marketable securities includes alternative investment securities of $2.4 million at September 30, 2015 and $8.5 million at December 31, 2014. Unrealized gains or losses on alternative investments are recognized in the Equity (loss) earnings on alternative investments line of the Company’s Consolidated Statements of Income.