March 31, 2019 were analyzed for OTTI. Based upon this analysis, the Company believes that, as of March 31, 2019, such securities with unrealized losses do not represent impairments that are other-than-temporary.

The following tables present the amortized cost, gross unrealized gains, gross unrealized losses and the fair value for available for sale debt securities at March 31, 2019 and December 31, 2018 (in thousands):


	March 31, 2019
	Amortized cost		Gross unrealized gains	Gross unrealized losses	Fair value



Mortgage-backed securities	$	1,057,405	5,205	(8,128)	1,054,482
State and municipal obligations	3,944		144	—	4,088
Corporate obligations	25,037		92	(98)	25,031

	$	1,086,386	5,441	(8,226)	1,083,601


	December 31, 2018
	Amortized cost		Gross unrealized gains	Gross unrealized losses	Fair value



Mortgage-backed securities	$	1,048,415	2,704	(16,150)	1,034,969
State and municipal obligations	2,828		84	—	2,912
Corporate obligations	25,039		268	(109)	25,198

	$	1,076,282	3,056	(16,259)	1,063,079

The amortized cost and fair value of available for sale debt securities at March 31, 2019, by contractual maturity, are shown below (in thousands). Expected maturities may differ from contractual maturities due to prepayment or early call privileges of the issuer.


	March 31, 2019
	Amortized cost		Fair Value
Due in one year or less	$	—	—
Due after one year through five years	3,005		3,027
Due after five years through ten years	25,976		26,092
Due after ten years	—		—
	$	28,981	29,119

Mortgage-backed securities totaling $1.06 billion at amortized cost and $1.05 billion at fair value are excluded from the table above as their expected lives are likely to be shorter than the contractual maturity date due to principal prepayments.

The following tables present the fair values and gross unrealized losses for available for sale debt securities with temporary impairment at March 31, 2019 and December 31, 2018 (in thousands):


	March 31, 2019 Unrealized Losses
	Less than 12 months				12 months or longer			Total
	Fair value		Gross unrealized losses	Fair value	Gross unrealized losses	Fair Value	Gross unrealized losses


Mortgage-backed securities	$	5,066	(1)	591,692	(8,127)	596,758	(8,128)

Corporate obligations	—		—	4,902	(98)	4,902	(98)
	$	5,066	(1)	596,594	(8,225)	601,660	(8,226)


	December 31, 2018 Unrealized Losses
	Less than 12 months				12 months or longer			Total
	Fair value		Gross unrealized losses	Fair value	Gross unrealized losses	Fair value	Gross unrealized losses



Mortgage-backed securities	$	218,175	(2,173)	545,880	(13,977)	764,055	(16,150)

Corporate obligations	7,897		(109)	—	—	7,897	(109)
	$	226,072	(2,282)	545,880	(13,977)	771,952	(16,259)

The number of available for sale debt securities in an unrealized loss position at March 31, 2019 totaled 130, compared with 175 at December 31, 2018. The decrease in the number of securities in an unrealized loss position at March 31, 2019 was due to lower current market interest rates compared to rates at December 31, 2018. All temporarily impaired securities were investment grade at March 31, 2019. At March 31, 2019, there was one private label mortgage-backed security in an unrealized loss position, with an amortized cost of $24,000 and an unrealized loss of $2,000. This private label mortgage-backed security was investment grade at March 31, 2019.

Based on its detailed review of the available for sale debt securities portfolio, the Company believes that as of March 31, 2019, securities with unrealized loss positions shown above do not represent impairments that are other-than-temporary. The Company does not have the intent to sell securities in a temporary loss position at March 31, 2019, nor is it more likely than not that the Company will be required to sell the securities before the anticipated recovery.

The following tables present the amortized cost, gross unrealized gains, gross unrealized losses and the estimated fair value for held to maturity debt securities at March 31, 2019 and December 31, 2018 (in thousands):


	March 31, 2019
	Amortized cost		Gross unrealized gains	Gross unrealized losses	Fair value
Agency obligations	$	4,620	6	(56)	4,570
Mortgage-backed securities	170		3	—	173
State and municipal obligations	456,554		8,850	(957)	464,447
Corporate obligations	10,695		14	(72)	10,637
	$	472,039	8,873	(1,085)	479,827


	December 31, 2018
	Amortized cost		Gross unrealized gains	Gross unrealized losses	Fair Value
Agency obligations	$	4,989	1	(94)	4,896
Mortgage-backed securities	187		3	—	190
State and municipal obligations	463,801		4,329	(3,767)	464,363
Corporate obligations	10,448		1	(158)	10,291
	$	479,425	4,334	(4,019)	479,740

The Company generally purchases securities for long-term investment purposes, and differences between amortized cost and fair values may fluctuate during the investment period. There were no sales of securities from the held to maturity debt securities portfolio for the three months ended March 31, 2019 and 2018. For the three months ended March 31, 2019, proceeds from calls on securities in the held to maturity debt securities portfolio totaled $9.3 million with no gross gains and no gross losses. For the three months ended March 31, 2018, proceeds from calls of securities in the held to maturity debt securities portfolio totaled $20.3 million with gross gains of $1,000 and no gross loss recognized.

The amortized cost and fair value of investment securities in the held to maturity debt securities portfolio at March 31, 2019 by contractual maturity are shown below (in thousands). Expected maturities may differ from contractual maturities due to prepayment or early call privileges of the issuer.


	March 31, 2019
	Amortized cost		Fair value
Due in one year or less	$	10,605	10,620
Due after one year through five years	89,791		90,661
Due after five years through ten years	263,184		267,797
Due after ten years	108,289		110,576
	$	471,869	479,654

Mortgage-backed securities totaling $170,000 at amortized cost and $173,000 at fair value are excluded from the table above as their expected lives are likely to be shorter than the contractual maturity date due to principal prepayments.

The following tables present the fair value and gross unrealized losses for held to maturity debt securities with temporary impairment at March 31, 2019 and December 31, 2018 (in thousands):


	March 31, 2019 Unrealized Losses
	Less than 12 months				12 months or longer			Total
	Fair value		Gross unrealized losses	Fair value	Gross unrealized losses	Fair value	Gross unrealized losses
Agency obligations	$	3,652	(56)	—	—	3,652	(56)
State and municipal obligations	4,357		(31)	54,654	(926)	59,011	(957)
Corporate obligations	8,131		(72)	—	—	8,131	(72)
	$	16,140	(159)	54,654	(926)	70,794	(1,085)


	December 31, 2018 Unrealized Losses
	Less than 12 months				12 months or longer			Total
	Fair value		Gross unrealized losses	Fair value	Gross unrealized losses	Fair value	Gross unrealized losses
Agency obligations	$	—	—	4,525	(94)	4,525	(94)
State and municipal obligations	96,412		(918)	81,663	(2,849)	178,075	(3,767)
Corporate obligations	—		—	9,004	(158)	9,004	(158)
	$	96,412	(918)	95,192	(3,101)	191,604	(4,019)

Based on its detailed review of the held to maturity debt securities portfolio, the Company believes that as of March 31, 2019, securities with unrealized loss positions shown above do not represent impairments that are other-than-temporary. The Company does not have the intent to sell securities in a temporary loss position at March 31, 2019, nor is it more likely than not that the Company will be required to sell the securities before the anticipated recovery.

The number of held to maturity debt securities in an unrealized loss position at March 31, 2019 totaled 130, compared with 334 at December 31, 2018. The decrease in the number of securities in an unrealized loss position at March 31, 2019, was due to lower current market interest rates compared to rates at December 31, 2018. All temporarily impaired investment securities were investment grade at March 31, 2019.