Note 3. Securities

The amortized cost and fair value of securities classified as available for sale and held to maturity at December 31, 2018 and 2017 follow.



Securities Available for Sale
	December 31, 2018								December 31, 2017
			Gross		Gross						Gross		Gross
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
(in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury and government agency securities	$	74,339	$	—	$	2,633	$	71,706	$	99,535	$	—	$	2,263	$	97,272
Municipal obligations		246,713		360		6,646		240,427		245,997		1,135		3,346		243,786
Residential mortgage-backed securities		1,468,912		4,284		29,794		1,443,402		1,729,989		5,611		20,387		1,715,213
Commercial mortgage-backed securities		799,060		1,953		30,936		770,077		704,518		480		17,863		687,135
Collateralized mortgage obligations		163,282		903		2,260		161,925		165,518		4		1,559		163,963
Corporate debt securities		3,500		—		—		3,500		3,500		—		—		3,500
	$	2,755,806	$	7,500	$	72,269	$	2,691,037	$	2,949,057	$	7,230	$	45,418	$	2,910,869



Securities Held to Maturity
	December 31, 2018								December 31, 2017
			Gross		Gross						Gross		Gross
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
(in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury and government agency securities	$	50,000	$	—	$	478	$	49,522	$	50,000	$	—	$	289	$	49,711
Municipal obligations		688,201		2,347		9,503		681,045		723,094		8,323		4,245		727,172
Residential mortgage-backed securities		640,393		1,461		6,117		635,737		725,748		4,175		2,690		727,233
Commercial mortgage-backed securities		357,175		376		10,882		346,669		317,185		40		3,915		313,310
Collateralized mortgage obligations		1,243,778		1,598		22,493		1,222,883		1,161,484		572		17,472		1,144,584
	$	2,979,547	$	5,782	$	49,473	$	2,935,856	$	2,977,511	$	13,110	$	28,611	$	2,962,010

The following tables present the amortized cost and fair value of debt securities at December 31, 2018 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	$	1,862	$	1,868
Due after one year through five years		105,364		106,255
Due after five years through ten years		1,200,188		1,163,870
Due after ten years		1,448,392		1,419,044
Total available for sale debt securities	$	2,755,806	$	2,691,037



(in thousands)	Amortized Cost		Fair Value
Debt Securities Held to Maturity
Due in one year or less	$	18,654	$	18,676
Due after one year through five years		127,861		126,495
Due after five years through ten years		1,425,846		1,405,836
Due after ten years		1,407,186		1,384,849
Total held to maturity debt securities	$	2,979,547	$	2,935,856

The Company held no securities classified as trading at December 31, 2018 or 2017.

The details for securities classified as available for sale with unrealized losses as of December 31, 2018 follow.



Available for sale
	Losses < 12 Months				Losses 12 Months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	—	$	—	$	71,706	$	2,633	$	71,706	$	2,633
Municipal obligations		41,203		591		170,883		6,054		212,086		6,645
Residential mortgage-backed securities		305,090		2,485		762,826		27,309		1,067,916		29,794
Commercial mortgage-backed securities		96,226		1,851		570,485		29,085		666,711		30,936
Collateralized mortgage obligations		254		1		111,804		2,259		112,058		2,260
	$	442,773	$	4,928	$	1,687,704	$	67,340	$	2,130,477	$	72,268

The details for securities classified as available for sale with unrealized losses as of December 31, 2017 follow.



Available for sale
	Losses < 12 Months				Losses 12 Months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	45,616	$	42	$	51,157	$	2,221	$	96,773	$	2,263
Municipal obligations		2,768		11		173,530		3,335		176,298		3,346
Residential mortgage-backed securities		461,835		4,195		898,099		16,192		1,359,934		20,387
Commercial mortgage-backed securities		203,618		995		411,046		16,868		614,664		17,863
Collateralized mortgage obligations		128,174		1,076		35,488		483		163,662		1,559
	$	842,011	$	6,319	$	1,569,320	$	39,099	$	2,411,331	$	45,418

The details for securities classified as held to maturity with unrealized losses as of December 31, 2018 follow.



Held to maturity
	Losses < 12 Months				Losses 12 Months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	—	$	—	$	49,521	$	478	$	49,521	$	478
Municipal obligations		233,469		2,256		233,280		7,247		466,749		9,503
Residential mortgage-backed securities		90,730		123		235,251		5,994		325,981		6,117
Commercial mortgage-backed securities		—		—		305,419		10,882		305,419		10,882
Collateralized mortgage obligations		77,394		281		897,153		22,212		974,547		22,493
	$	401,593	$	2,660	$	1,720,624	$	46,813	$	2,122,217	$	49,473

The details for securities classified as held to maturity with unrealized losses as of December 31, 2017 follow.



Held to maturity
	Losses < 12 Months				Losses 12 Months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	—	$	—	$	49,711	$	289	$	49,711	$	289
Municipal obligations		14,603		19		230,960		4,226		245,563		4,245
Residential mortgage-backed securities		8,815		99		230,277		2,591		239,092		2,690
Commercial mortgage-backed securities		174,882		744		72,499		3,171		247,381		3,915
Collateralized mortgage obligations		570,289		5,653		472,536		11,819		1,042,825		17,472
	$	768,589	$	6,515	$	1,055,983	$	22,096	$	1,824,572	$	28,611

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 on these debt securities would be recovered no later than 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 issuers’ abilities to meet contractual obligations. The Company believes it 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.

The following table presents the proceeds from and gross gains and gross losses on sales of securities during the years ended December 31, 2018, 2017 and 2016:



	Years Ended December 31,
(in thousands)	2018		2017		2016
Proceeds	$	455,162	$	213,877	$	173,215
Gross gains		—		—		1,965
Gross losses		25,480		—		211

Securities with carrying values totaling approximately $3.4 billion at December 31, 2018 and $3.3 billion at December 31, 2017 were pledged, primarily to secure public deposits or securities sold under agreements to repurchase.