Note 2. Securities

The amortized cost and fair value of securities classified as available for sale and held to maturity follow:


Securities Available for Sale
	December 31, 2015								December 31, 2014
in thousands	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury and government agency securities	$	135	$	—	$	1	$	134	$	300,207	$	372	$	71	$	300,508
Municipal obligations		39,410		235		38		39,607		13,995		186		5		14,176
Mortgage-backed securities		1,750,168		19,387		11,182		1,758,373		1,217,293		31,094		2,823		1,245,564
Collateralized mortgage obligations		291,085		140		2,192		289,033		88,093		—		1,229		86,864
Corporate debt securities		3,500		—		—		3,500		3,500		—		—		3,500
Equity securities		2,447		358		48		2,757		8,673		891		11		9,553

	$	2,086,745	$	20,120	$	13,461	$	2,093,404	$	1,631,761	$	32,543	$	4,139	$	1,660,165


Securities Held to Maturity
	December 31, 2015								December 31, 2014
in thousands	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury and government agency securities	$	50,000	$	—	$	410	$	49,590	$	—	$	—	$	—	$	—
Municipal obligations		185,890		3,475		1,166		188,199		180,615		3,416		1,144		182,887
Mortgage-backed securities		1,014,135		15,585		1,589		1,028,131		899,923		23,897		162		923,658
Collateralized mortgage obligations		1,120,363		2,244		12,676		1,109,931		1,085,751		5,590		11,546		1,079,795

	$	2,370,388	$	21,304	$	15,841	$	2,375,851	$	2,166,289	$	32,903	$	12,852	$	2,186,340

The following table presents the amortized cost and fair value of debt securities at December 31, 2015 by contractual maturity. Actual maturities will differ from contractual maturities because of rights to call or repay obligations with or without penalties and scheduled and unscheduled principal payments on mortgage-backed securities and collateral mortgage obligations.


in thousands	Amortized Cost		Fair Value
Debt Securities Available for Sale
Due in one year or less	$	42,807	$	41,901
Due after one year through five years		71,342		72,447
Due after five years through ten years		322,891		330,327
Due after ten years		1,647,258		1,645,972

Total available for sale debt securities	$	2,084,298	$	2,090,647


in thousands	Amortized Cost		Fair Value
Debt Securities Held to Maturity
Due in one year or less	$	113,296	$	111,710
Due after one year through five years		430,315		425,060
Due after five years through ten years		137,021		136,244
Due after ten years		1,689,756		1,702,837

Total held to maturity debt securities	$	2,370,388	$	2,375,851

The Company held no securities classified as trading at December 31, 2015 or 2014.

The details for securities classified as available for sale with unrealized losses as of December 31, 2015 follow:


Available for sale
	Losses < 12 months				Losses 12 months or >				Total
in thousands	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. Treasury and government agency securities	$	—	$	—	$	82	$	1	$	82	$	1
Municipal obligations		8,296		38		—		—		8,296		38
Mortgage-backed securities		831,156		8,257		116,126		2,925		947,282		11,182
Collateralized mortgage obligations		208,397		1,257		33,138		935		241,535		2,192
Equity securities		20		1		1,473		47		1,493		48

	$	1,047,869	$	9,553	$	150,819	$	3,908	$	1,198,688	$	13,461

The details for securities classified as available for sale with unrealized losses as of December 31, 2014 follow:


Available for sale
	Losses < 12 months				Losses 12 months or >				Total
in thousands	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. Treasury and government agency securities	$	99,950	$	70	$	121	$	1	$	100,071	$	71
Municipal obligations		2,995		5		—		—		2,995		5
Mortgage-backed securities		38,955		163		125,641		2,660		164,596		2,823
Collateralized mortgage obligations		—		—		86,864		1,229		86,864		1,229
Equity securities		5,998		10		3		1		6,001		11

	$	147,898	$	248	$	212,629	$	3,891	$	360,527	$	4,139

The details for securities classified as held to maturity with unrealized losses as of December 31, 2015 follow:


Held to maturity
	Losses < 12 months				Losses 12 months or >				Total
in thousands	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. Treasury and government agency securities	$	45,590	$	410	$	—	$	—	$	45,590	$	410
Municipal obligations		22,652		301		48,727		865		71,379		1,166
Mortgage-backed securities		349,635		1,589		—		—		349,635		1,589
Collateralized mortgage obligations		516,330		2,894		370,756		9,782		887,086		12,676

	$	934,207	$	5,194	$	419,483	$	10,647	$	1,353,690	$	15,841

The details for securities classified as held to maturity with unrealized losses as of December 31, 2014 follow:


Held to maturity
	Losses < 12 months				Losses 12 months or >				Total
in thousands	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Municipal obligations	$	4,316	$	12	$	58,105	$	1,132	$	62,421	$	1,144
Mortgage-backed securities		—		—		95,522		162		95,522		162
Collateralized mortgage obligations		119,222		616		540,607		10,930		659,829		11,546

	$	123,538	$	628	$	694,234	$	12,224	$	817,772	$	12,852

The unrealized losses primarily relate to changes in market rates on fixed-rate debt securities since the respective purchase date. In all cases, the indicated impairment would be recovered by the security’s maturity date or possibly earlier if the market price for the security increases with a reduction in the yield required by the market. None of the unrealized losses relate to the marketability of the securities or the issuer’s ability to meet contractual obligations. The Company has adequate liquidity and, therefore, does not plan to and, more likely than not, will not be required to sell these securities before recovery of the indicated impairment. Accordingly, the unrealized losses on these securities have been determined to be temporary.

Proceeds from sales of securities available for sale were approximately $6.6 million in 2015, $1.5 million in 2014, and $0.2 million in 2013. Realized gross gains and losses, computed through specific identification, were insignificant. The net carrying amount of held to maturity securities that were sold in 2015 was $2.6 million with an associated realized gain of $0.2 million. The securities were sold because they were downgraded, and there was a concern that they would fall below the Company’s investment grade policy threshold.

Securities with carrying values totaling approximately $3.5 billion at December 31, 2015 and $3.2 billion at December 31, 2014 were pledged primarily to secure public deposits or sold under agreements to repurchase.