Securities Available for Sale

The following is a summary of securities available for sale as of the dates indicated:



	At March 31, 2017
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(Dollars in thousands)
Debt securities:
U.S. Government agency and U.S. Government sponsored enterprises
Debt securities	$	10,002	$	—	$	(4	)	$	9,998
Collateralized mortgage obligations (residential)	736,000		406		(9,787		)	726,619
Mortgage-backed securities (residential)	744,654		1,252		(13,214		)	732,692
Corporate securities	4,564		—		(251		)	4,313
Municipal securities	97,689		609		(1,044		)	97,254
Total debt securities	1,592,909		2,267		(24,300		)	1,570,876
Mutual funds	13,425		18		(373		)	13,070
Total investment securities available for sale	$	1,606,334	$	2,285	$	(24,673	)	$	1,583,946

	At December 31, 2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(Dollars in thousands)
Debt securities:
U.S. Government agency and U.S. Government sponsored enterprises
Debt securities	$	12,005	$	3	$	—		$	12,008
Collateralized mortgage obligations (residential)	715,981		349		(10,663		)	705,667
Mortgage-backed securities (residential)	741,304		1,132		(14,395		)	728,041
Corporate securities	11,576		—		(449		)	11,127
Municipal securities	88,018		358		(1,537		)	86,839
Total debt securities	1,568,884		1,842		(27,044		)	1,543,682
Mutual funds	13,425		—		(367		)	13,058
Total investment securities available for sale	$	1,582,309	$	1,842	$	(27,411	)	$	1,556,740

As of March 31, 2017 and December 31, 2016, there were no holdings of securities of any one issuer, other than the U.S. Government and its agencies, in an amount greater than 10% of stockholders’ equity.

For the three months ended March 31, 2017 and 2016, $3.2 million and $15.6 million, respectively, of unrealized gains were included in accumulated other comprehensive income (loss). No investments were sold during the three months ended March 31, 2017 and 2016.

The amortized cost and estimated fair value of investment securities at March 31, 2017, by contractual maturity, are shown below. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Securities not due at a single maturity date are shown separately.



	Amortized Cost		Estimated Fair Value
	(Dollars in thousands)
Available for sale:
Due within one year	$	10,724	$	10,725
Due after one year through five years	7,472		7,630
Due after five years through ten years	40,905		40,891
Due after ten years	53,154		52,319
U.S. Government agency and U.S. Government sponsored enterprises
Collateralized mortgage obligations (residential)	736,000		726,619
Mortgage-backed securities (residential)	744,654		732,692
Mutual funds	13,425		13,070
Total	$	1,606,334	$	1,583,946

Securities with carrying values of approximately $366.1 million and $382.1 million at March 31, 2017 and December 31, 2016, respectively, were pledged to secure public deposits, various borrowings and for other purposes as required or permitted by law.

The following tables show our investments’ gross unrealized losses and estimated fair value, aggregated by investment category and the length of time that the individual securities have been in a continuous unrealized loss position as of the dates indicated.



	As of March 31, 2017
	Less than 12 months						12 months or longer						Total
Description of Securities	Number of Securities	Fair Value		Gross Unrealized Losses			Number of Securities	Fair Value		Gross Unrealized Losses			Number of Securities	Fair Value		Gross Unrealized Losses
	(Dollars in thousands)
Debt securities*	3	$	9,998	$	(4	)	—	$	—	$	—		3	$	9,998	$	(4	)
Collateralized mortgage obligations (residential)*	67	624,327		(8,668		)	4	34,843		(1,119		)	71	659,170		(9,787		)
Mortgage-backed securities (residential)*	59	606,378		(13,214		)	—	—		—			59	606,378		(13,214		)
Corporate securities	—	—		—			1	4,313		(251		)	1	4,313		(251		)
Municipal securities	54	50,447		(1,018		)	1	509		(26		)	55	50,956		(1,044		)
Mutual funds	3	11,590		(373		)	—	—		—			3	11,590		(373		)
Total	186	$	1,302,740	$	(23,277	)	6	$	39,665	$	(1,396	)	192	$	1,342,405	$	(24,673	)

__________________________________

* Investments in U.S. Government agency and U.S. Government sponsored enterprises



	As of December 31, 2016
	Less than 12 months						12 months or longer						Total
Description of Securities	Number of Securities	Fair Value		Gross Unrealized Losses			Number of Securities	Fair Value		Gross Unrealized Losses			Number of Securities	Fair Value		Gross Unrealized Losses
	(Dollars in thousands)
Collateralized mortgage obligations (residential)*	66	$	615,803	$	(9,459	)	4	$	36,333	$	(1,204	)	70	$	652,136	$	(10,663	)
Mortgage-backed securities (residential)*	57	622,797		(14,395		)	—	—		—			57	622,797		(14,395		)
Corporate securities	1	7,014		(2		)	1	4,113		(447		)	2	11,127		(449		)
Municipal securities	95	69,331		(1,537		)	—	—		—			95	69,331		(1,537		)
Mutual funds	3	13,058		(367		)	—	—		—			3	13,058		(367		)
Total	222	$	1,328,003	$	(25,760	)	5	$	40,446	$	(1,651	)	227	$	1,368,449	$	(27,411	)

__________________________________

* Investments in U.S. Government agency and U.S. Government sponsored enterprises

The Company evaluates securities for other-than-temporary-impairment (“OTTI”) on at least a quarterly basis, and more frequently when economic or market concerns warrant such evaluation. Consideration is given to the financial condition and near-term prospects of the issuer, the length of time and the extent to which the fair values of the securities have been less than the cost of the securities, and management’s intention to sell, or whether it is more likely than not that management will be required to sell a security in an unrealized loss position before recovery of its amortized cost basis. In analyzing an issuer’s financial condition, the Company considers, among other considerations, whether the securities are issued by the federal government or its agencies, whether downgrades by bond rating agencies have occurred, and the results of reviews of the issuer’s financial condition.

The Company has certain corporate securities, collateralized mortgage obligations, and municipal securities that were in a continuous unrealized loss position for twelve months or longer as of March 31, 2017. The corporate securities at March 31, 2017 had a total amortized cost of $4.6 million and an unrealized loss of $251 thousand at March 31, 2017. These corporate securities are scheduled to mature in May 2047. These securities were rated investment grade and there were no credit quality concerns with the issuer. The collateralized mortgage obligations in a continuous loss position for twelve months or longer had an unrealized loss of $1.1 million at March 31, 2017. These securities were issued by U.S. Government agency and U.S. Government sponsored enterprises and have high credit ratings of “AA” grade or better. Interest on the corporate securities and the U.S. Government agency and U.S. Government sponsored enterprise investments have been paid as agreed, and management believes this will continue in the future and that the securities will be repaid in full as scheduled. Municipal securities that were in a continuous loss position for twelve months or longer had an unrealized loss of $26 thousand at March 31, 2017. The market value declines for these securities were primarily due to movements in interest rates and are not reflective of management’s expectations of the Company’s ability to fully recover these investments, which may be at maturity. For these reasons, no OTTI was recognized on the corporate and municipal securities and the U.S. Government agency and U.S. Government sponsored collateralized mortgage obligations that were in an unrealized loss position at March 31, 2017.

The Company considers the losses on the investments in unrealized loss positions at March 31, 2017 to be temporary based on: 1) the likelihood of recovery; 2) the information relative to the extent and duration of the decline in market value; and 3) the Company’s intention not to sell, and management’s determination that it is more likely than not that the Company will not be required to sell a security in an unrealized loss position before recovery of its amortized cost basis.