SECURITIES

A summary of the Company's securities portfolio by category and maturity is presented in the following tables.

Securities Portfolio

(Dollar amounts in thousands)



	As of December 31,
	2016									2015
	Amortized Cost		Gross Unrealized					Fair Value		Amortized Cost		Gross Unrealized					Fair Value
	Amortized Cost		Gains		Losses			Fair Value		Amortized Cost		Gains		Losses			Fair Value
Securities Available-for-Sale
U.S. treasury securities	$	48,581	$	26	$	(66	)	$	48,541	$	17,000	$	15	$	(35	)	$	16,980
U.S. agency securities	183,528		519		(410		)	183,637		86,461		351		(169		)	86,643
Collateralized mortgage obligations ("CMOs")	1,064,130		969		(17,653		)	1,047,446		695,198		1,072		(9,085		)	687,185
Other mortgage-backed securities ("MBSs")	337,139		1,395		(5,879		)	332,655		152,481		1,920		(871		)	153,530
Municipal securities	273,319		1,245		(3,718		)	270,846		321,437		6,443		(310		)	327,570
Trust-preferred collateralized debt obligations ("CDOs")	47,681		261		(14,682		)	33,260		48,287		34		(16,792		)	31,529
Equity securities	3,206		147		(288		)	3,065		3,282		86		(169		)	3,199
Total securities available-for-sale	$	1,957,584	$	4,562	$	(42,696	)	$	1,919,450	$	1,324,146	$	9,921	$	(27,431	)	$	1,306,636
Securities Held-to-Maturity
Municipal securities	$	22,291	$	—	$	(4,079	)	$	18,212	$	23,152	$	—	$	(3,098	)	$	20,054
Trading Securities								$	17,920								$	16,894

Remaining Contractual Maturity of Securities

(Dollar amounts in thousands)



	As of December 31, 2016
	Available-for-Sale				Held-to-Maturity
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
One year or less	$	73,669	$	71,428	$	2,336	$	1,909
After one year to five years	429,166		416,112		6,834		5,583
After five years to ten years	2,592		2,513		2,975		2,431
After ten years	47,682		46,231		10,146		8,289
Securities that do not have a single contractual maturity date	1,404,475		1,383,166		—		—
Total	$	1,957,584	$	1,919,450	$	22,291	$	18,212

The carrying value of securities available-for-sale that were pledged to secure deposits or for other purposes as permitted or required by law totaled $1.1 billion as of December 31, 2016 and $856.9 million as of December 31, 2015. No securities held-to-maturity were pledged as of December 31, 2016 or 2015.

Excluding securities issued or backed by the U.S. government and its agencies and U.S. government-sponsored enterprises, there were no investments in securities from one issuer that exceeded 10% of total stockholders' equity as of December 31, 2016 or 2015.

During the years ended December 31, 2016, 2015, and 2014 there were no material gross trading gains (losses). The following table presents net realized gains on securities available-for-sale for the three years ended December 31, 2016.

Securities Available-for-Sale Gains

(Dollar amounts in thousands)



	Years Ended December 31,
	2016			2015			2014
Gains on sales of securities:
Gross realized gains	$	1,589		$	2,519		$	8,188
Gross realized losses	(169		)	(146		)	(63		)
Net realized gains on sales of securities	1,420			2,373			8,125
Non-cash impairment charges:
OTTI	—			—			(28		)
Net realized gains	$	1,420		$	2,373		$	8,097

During 2016, net securities gains consisted primarily of sales of municipal securities at gains of $1.1 million and sales of MBSs, CMOs, and equity securities at net gains of $304,000. Net securities gains consisted primarily of sales of MBSs at gains of $1.9 million and sales of CMOs, municipal securities, and other investments at net gains of $521,000 during 2015. The sale of a non-accrual CDO at a gain of $3.5 million and other investments at gains totaling $4.6 million comprised net securities gains during 2014.

Accounting guidance requires that the credit portion of an OTTI charge be recognized through income. If a decline in fair value below carrying value is not attributable to credit deterioration and the Company does not intend to sell the security or believe it would not be more likely than not required to sell the security prior to recovery, the Company records the non-credit related portion of the decline in fair value in other comprehensive (loss) income.

The following table presents a rollforward of life-to-date OTTI recognized in earnings related to all securities available-for-sale held by the Company for the years ended December 31, 2016, 2015, and 2014. The majority of the beginning and ending balance of OTTI relates to CDOs currently held by the Company.

Changes in OTTI Recognized in Earnings

(Dollar amounts in thousands)



	Years Ended December 31,
	2016		2015			2014
Beginning balance	$	23,345	$	23,516		$	32,422
OTTI included in earnings ⁽¹⁾:
Losses on securities that previously had OTTI	—		—			28
Losses on securities that did not previously have OTTI	—		—			—
Reduction for securities sales ⁽²⁾	—		(171		)	(8,934		)
Ending balance	$	23,345	$	23,345		$	23,516


⁽¹⁾	Included in net securities gains in the Consolidated Statements of Income.


⁽²⁾	These reductions were driven by the sale of one CMO with a carrying value of $1.3 million during the year ended December 31, 2015 and one CDO with a carrying value of $1.3 million and one municipal security with a carrying value of $357,000 during the year ended December 31, 2014.

The following table presents the aggregate amount of unrealized losses and the aggregate related fair values of securities with unrealized losses as of December 31, 2016 and 2015.

Securities in an Unrealized Loss Position

(Dollar amounts in thousands)



		Less Than 12 Months				Greater Than 12 Months				Total
	Number of Securities	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
As of December 31, 2016
Securities Available-for-Sale
U.S. treasury securities	16	$	33,505	$	61	$	3,995	$	5	$	37,500	$	66
U.S. agency securities	28	62,064		364		11,814		46		73,878		410
CMOs	194	523,233		10,309		411,758		7,344		934,991		17,653
MBSs	68	221,174		4,726		77,780		1,154		298,954		5,880
Municipal securities	380	133,957		3,059		29,280		659		163,237		3,718
CDOs	7	—		—		30,592		14,682		30,592		14,682
Equity securities	2	404		201		2,319		86		2,723		287
Total	695	$	974,337	$	18,720	$	567,538	$	23,976	$	1,541,875	$	42,696
Securities Held-to-Maturity
Municipal securities	14	$	—	$	—	$	18,212	$	4,079	$	18,212	$	4,079

As of December 31, 2015
Securities Available-for-Sale
U.S. treasury securities	4	$	7,946	$	35	$	—	$	—	$	7,946	$	35
U.S. agency securities	10	30,620		169		—		—		30,620		169
CMOs	133	309,787		3,110		257,362		5,975		567,149		9,085
MBSs	27	63,028		427		31,980		444		95,008		871
Municipal securities	68	8,135		65		24,227		245		32,362		310
CDOs	8	8,034		971		21,642		15,821		29,676		16,792
Equity securities	2	485		120		2,305		49		2,790		169
Total	252	$	428,035	$	4,897	$	337,516	$	22,534	$	765,551	$	27,431
Securities Held-to-Maturity
Municipal securities	19	$	20,054	$	3,098	$	—	$	—	$	20,054	$	3,098

Substantially all of the Company's CMOs and other MBSs are either backed by U.S. government-owned agencies or issued by U.S. government-sponsored enterprises. Municipal securities are issued by municipal authorities, and the majority are supported by third-party insurance or some other form of credit enhancement. Management does not believe any of these securities with unrealized losses as of December 31, 2016 represent OTTI related to credit deterioration. These unrealized losses are attributed to changes in interest rates and temporary market movements. The Company does not intend to sell these securities and it is not more likely than not that the Company will be required to sell them before recovery of their amortized cost basis, which may be at maturity.

The unrealized losses on CDOs as of December 31, 2016 reflect changes in market activity for these securities. Management does not believe these unrealized losses represent OTTI related to credit deterioration. In addition, the Company does not intend to sell the CDOs with unrealized losses, and the Company does not believe it is more likely than not that it will be required to sell them before recovery of their amortized cost basis, which may be at maturity. Significant judgment is required to calculate the fair value of the CDOs. For a detailed discussion of the CDO valuation methodology, see Note 22, "Fair Value."