3. Securities

The amortized cost, estimated fair value and unrealized gains (losses) of available for sale ("AFS") securities are as follows:

(In thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
As of March 31, 2018
Federal agency	$	139,775	$	-	$	1,316	$	138,459
State & municipal		39,700		31		345		39,386
Mortgage-backed:
Government-sponsored enterprises		524,468		523		11,155		513,836
U.S. government agency securities		30,473		267		545		30,195
Collateralized mortgage obligations:
Government-sponsored enterprises		511,727		243		15,541		496,429
U.S. government agency securities		48,944		151		1,488		47,607
Total AFS securities	$	1,295,087	$	1,215	$	30,390	$	1,265,912
As of December 31, 2017
Federal agency	$	109,862	$	-	$	963	$	108,899
State & municipal		42,171		62		277		41,956
Mortgage-backed:
Government-sponsored enterprises		530,392		1,406		3,345		528,453
U.S. government agency securities		26,363		334		223		26,474
Collateralized mortgage obligations:
Government-sponsored enterprises		496,033		254		10,114		486,173
U.S. government agency securities		50,721		165		1,065		49,821
Equity securities		10,623		3,672		146		14,149
Total AFS securities	$	1,266,165	$	5,893	$	16,133	$	1,255,925

The amortized cost, estimated fair value and unrealized gains (losses) of securities held to maturity ("HTM") are as follows:

(In thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
As of March 31, 2018
Mortgage-backed:
Government-sponsored enterprises	$	93,769	$	-	$	2,749	$	91,020
U.S. government agency securities		389		47		-		436
Collateralized mortgage obligations:
Government-sponsored enterprises		188,260		-		5,004		183,256
State & municipal		204,708		292		2,303		202,697
Total HTM securities	$	487,126	$	339	$	10,056	$	477,409
As of December 31, 2017
Mortgage-backed:
Government-sponsored enterprises	$	96,357	$	85	$	810	$	95,632
U.S. government agency securities		418		57		-		475
Collateralized mortgage obligations:
Government-sponsored enterprises		186,327		224		2,577		183,974
State & municipal		200,971		1,439		620		201,790
Total HTM securities	$	484,073	$	1,805	$	4,007	$	481,871

Available for sale and held to maturity securities with amortized costs totaling $1.6 billion at March 31, 2018 and $1.5 billion at December 31, 2017 were pledged to secure public deposits and for other purposes required or permitted by law. Additionally, at March 31, 2018 and December 31, 2017, available for sale and held to maturity securities with an amortized cost of $218.3 million and $231.3 million, respectively, were pledged as collateral for securities sold under the repurchase agreements.

The following table sets forth information with regard to investment securities with unrealized losses segregated according to the length of time the securities had been in a continuous unrealized loss position:

	Less than 12 months							12 months or longer							Total
(In thousands)	Fair Value		Unrealized Losses			Number of Positions		Fair Value		Unrealized Losses			Number of Positions		Fair Value		Unrealized Losses			Number of Positions
As of March 31, 2018
AFS securities:
Federal agency	$	74,268	$	(459	)		6	$	64,191	$	(857	)		6	$	138,459	$	(1,316	)		12
State & municipal		25,927		(271	)		44		4,979		(74	)		7		30,906		(345	)		51
Mortgage-backed		440,714		(9,582	)		90		55,185		(2,118	)		25		495,899		(11,700	)		115
Collateralized mortgage obligations		249,512		(5,330	)		38		259,488		(11,699	)		43		509,000		(17,029	)		81
Total securities with unrealized losses	$	790,421	$	(15,642	)		178	$	383,843	$	(14,748	)		81	$	1,174,264	$	(30,390	)		259

HTM securities:
Mortgaged-backed	$	59,070	$	(1,344	)		4	$	31,950	$	(1,405	)		2	$	91,020	$	(2,749	)		6
Collateralized mortgage obligations		147,877		(2,864	)		23		35,379		(2,140	)		6		183,256		(5,004	)		29
State & municipal		74,241		(1,299	)		118		15,177		(1,004	)		24		89,418		(2,303	)		142
Total securities with unrealized losses	$	281,188	$	(5,507	)		145	$	82,506	$	(4,549	)		32	$	363,694	$	(10,056	)		177

As of December 31, 2017
AFS securities:
Federal agency	$	64,653	$	(242	)		5	$	44,246	$	(721	)		4	$	108,899	$	(963	)		9
State & municipal		23,566		(200	)		39		5,994		(77	)		8		29,560		(277	)		47
Mortgage-backed		317,630		(2,381	)		55		58,316		(1,187	)		24		375,946		(3,568	)		79
Collateralized mortgage obligations		227,917		(2,658	)		35		275,303		(8,521	)		42		503,220		(11,179	)		77
Equity securities		-		-			-		2,959		(146	)		1		2,959		(146	)		1
Total securities with unrealized losses	$	633,766	$	(5,481	)		134	$	386,818	$	(10,652	)		79	$	1,020,584	$	(16,133	)		213

HTM securities:
Mortgage -backed	$	15,477	$	(140	)		2	$	33,703	$	(670	)		2	$	49,180	$	(810	)		4
Collateralized mortgage obligations		118,476		(1,064	)		17		37,614		(1,513	)		6		156,090		(2,577	)		23
State & municipal		22,387		(132	)		40		15,720		(488	)		24		38,107		(620	)		64
Total securities with unrealized losses	$	156,340	$	(1,336	)		59	$	87,037	$	(2,671	)		32	$	243,377	$	(4,007	)		91

Declines in the fair value of HTM securities below their amortized cost, less any current period credit loss, that are deemed to be other-than-temporary are reflected in earnings as realized losses or in other comprehensive income. This classification is dependent upon whether the Company intends to sell the security, or whether it is more likely than not it will be required to sell the security before recovery. The other-than-temporary impairment ("OTTI") shall be recognized in earnings equal to the entire difference between the investment's amortized cost basis and its fair value at the balance sheet date. If the Company does not intend to sell the security and it is not more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the OTTI shall be separated into (a) the amount representing the credit loss and (b) the amount related to all other factors. The amount of the total OTTI related to the credit loss shall be recognized in earnings. The amount of the total OTTI related to other factors shall be recognized in other comprehensive income net of applicable taxes.

In estimating OTTI losses, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer and (iii) the historical and implied volatility of the fair value of the security.

Management has the intent to hold the securities classified as HTM until they mature, at which time it is believed the Company will receive full value for the securities. The unrealized losses on HTM debt securities are due to increases in market interest rates over yields at the time the underlying securities were purchased. When necessary, the Company has performed a discounted cash flow analysis to determine whether or not it will receive the contractual principal and interest on certain securities. The fair value is expected to recover as the bonds approach their maturity date or if market yields for such investments decline.

Management also has the intent to hold and will not be required to sell, the debt securities classified as AFS for a period of time sufficient for a recovery of cost, which may be until maturity. The unrealized losses on AFS debt securities are due to increases in market interest rates over the yields available at the time the underlying securities were purchased. When necessary, the Company has performed a discounted cash flow analysis to determine whether or not it will receive the contractual principal and interest on certain securities. For AFS debt securities, OTTI losses are recognized in earnings if the Company intends to sell the security. In other cases the Company considers the relevant factors noted above, as well as the Company's intent and ability to retain its investment for a period of time sufficient to allow for any anticipated recovery in market value and whether evidence exists to support a realizable value equal to or greater than the cost basis. Any impairment loss on an equity security is equal to the full difference between the cost basis and the fair value of the security.

As of March 31, 2018 and December 31, 2017, management believes the impairments detailed in the table above are temporary. There were no OTTI losses realized in the Company's consolidated statement of income for the quarter ended March 31, 2018. For the quarter ended March 31, 2017, a $1.3 million impairment loss on an equity investment was realized in the Company's consolidated statements of income.

The following tables set forth information with regard to gains and losses on equity securities for the quarter ended March 31, 2018:

(In thousands)
Net gains and losses recognized on equity securities	$	72
Less: Net gains and losses recognized during the period on equity securities sold during the period		44
Unrealized gains and losses recognized on equity securities still held at March 31, 2018	$	28

As of March 31, 2018, the carrying value of equity securities without readily determinable fair values was $5.0 million. The Company performed a qualitative assessment to determine whether the investments were impaired and identified no areas of concern as of March 31, 2018. There were no impairments, downward or upward adjustments recognized for equity securities without readily determinable fair values during the quarter ended March 31, 2018.

The following tables set forth information with regard to contractual maturities of debt securities at March 31, 2018:

(In thousands)	Amortized Cost		Estimated Fair Value
AFS debt securities:
Within one year	$	99,647	$	99,288
From one to five years		82,353		81,136
From five to ten years		175,040		172,862
After ten years		938,047		912,626
Total AFS debt securities	$	1,295,087	$	1,265,912
HTM debt securities:
Within one year	$	37,885	$	37,885
From one to five years		43,089		43,159
From five to ten years		208,715		204,710
After ten years		197,437		191,655
Total HTM debt securities	$	487,126	$	477,409

Maturities of mortgage-backed, collateralized mortgage obligations and asset-backed securities are stated based on their estimated average lives. Actual maturities may differ from estimated average lives or contractual maturities because, in certain cases, borrowers have the right to call or prepay obligations with or without call or prepayment penalties.

Except for U.S. Government securities, there were no holdings, when taken in the aggregate, of any single issuer that exceeded 10% of consolidated stockholders' equity at March 31, 2018 and December 31, 2017.