Investment Securities

The following tables are a summary of the available-for-sale and held-to-maturity securities portfolios as of the dates shown:



	June 30, 2016
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Available-for-sale securities
U.S. Treasury	$	122,296	$	35	$	(1	)	$	122,330
U.S. Government agencies	69,678		238		—			69,916
Municipal	108,179		3,588		(127		)	111,640
Corporate notes:
Financial issuers	68,097		1,502		(1,411		)	68,188
Other	1,500		2		—			1,502
Mortgage-backed: ⁽¹⁾
Mortgage-backed securities	162,593		4,280		(150		)	166,723
Collateralized mortgage obligations	40,419		457		(91		)	40,785
Equity securities	51,426		5,544		(391		)	56,579
Total available-for-sale securities	$	624,188	$	15,646	$	(2,171	)	$	637,663
Held-to-maturity securities
U.S. Government agencies	$	789,482	$	11,861	$	(647	)	$	800,696
Municipal	202,729		6,967		(213		)	209,483
Total held-to-maturity securities	$	992,211	$	18,828	$	(860	)	$	1,010,179



	December 31, 2015
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Available-for-sale securities
U.S. Treasury	$	312,282	$	—	$	(5,553	)	$	306,729
U.S. Government agencies	70,313		198		(275		)	70,236
Municipal	105,702		3,249		(356		)	108,595
Corporate notes:
Financial issuers	80,014		1,510		(1,481		)	80,043
Other	1,500		4		(2		)	1,502
Mortgage-backed: ⁽¹⁾
Mortgage-backed securities	1,069,680		3,834		(21,004		)	1,052,510
Collateralized mortgage obligations	40,421		172		(506		)	40,087
Equity securities	51,380		5,799		(493		)	56,686
Total available-for-sale securities	$	1,731,292	$	14,766	$	(29,670	)	$	1,716,388
Held-to-maturity securities
U.S. Government agencies	$	687,302	$	4	$	(7,144	)	$	680,162
Municipal	197,524		867		(442		)	197,949
Total held-to-maturity securities	$	884,826	$	871	$	(7,586	)	$	878,111



	June 30, 2015
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
(Dollars in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Available-for-sale securities
U.S. Treasury	$	288,196	$	138	$	(7,173	)	$	281,161
U.S. Government agencies	651,737		2,074		(25,151		)	628,660
Municipal	269,562		4,222		(3,994		)	269,790
Corporate notes:
Financial issuers	124,924		1,773		(1,289		)	125,408
Other	2,726		9		(2		)	2,733
Mortgage-backed: ⁽¹⁾
Mortgage-backed securities	777,087		4,053		(23,499		)	757,641
Collateralized mortgage obligations	42,550		342		(432		)	42,460
Equity securities	48,740		5,876		(408		)	54,208
Total available-for-sale securities	$	2,205,522	$	18,487	$	(61,948	)	$	2,162,061
Held-to-maturity securities
U.S. Government agencies	$	—	$	—	$	—		$	—
Municipal	—		—		—			—
Total held-to-maturity securities	$	—	$	—	$	—		$	—


(1)	Consisting entirely of residential mortgage-backed securities, none of which are subprime.

In the fourth quarter of 2015, the Company transferred $862.7 million of investment securities with an unrealized loss of $14.4 million from the available-for-sale classification to the held-to-maturity classification. No investment securities were transferred from the available-for-sale classification to the held-to-maturity classification in the first six months of 2016.

The following table presents the portion of the Company’s available-for-sale and held-to-maturity securities portfolios which has gross unrealized losses, reflecting the length of time that individual securities have been in a continuous unrealized loss position at June 30, 2016:



	Continuous unrealized losses existing for less than 12 months					Continuous unrealized losses existing for greater than 12 months					Total
(Dollars in thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Available-for-sale securities
U.S. Treasury	$	2,250	$	(1	)	$	—	$	—		$	2,250	$	(1	)
U.S. Government agencies	—		—			—		—			—		—
Municipal	10,789		(16		)	7,701		(111		)	18,490		(127		)
Corporate notes:
Financial issuers	19,822		(178		)	24,727		(1,233		)	44,549		(1,411		)
Other	—		—			—		—			—		—
Mortgage-backed:
Mortgage-backed securities	—		—			4,089		(150		)	4,089		(150		)
Collateralized mortgage obligations	2,528		(15		)	6,433		(76		)	8,961		(91		)
Equity securities	1,897		(121		)	8,791		(270		)	10,688		(391		)
Total available-for-sale securities	$	37,286	$	(331	)	$	51,741	$	(1,840	)	$	89,027	$	(2,171	)
Held-to-maturity securities
U.S. Government agencies	$	134,808	$	(647	)	$	—	$	—		$	134,808	$	(647	)
Municipal	12,172		(172		)	3,313		(41		)	15,485		(213		)
Total held-to-maturity securities	$	146,980	$	(819	)	$	3,313	$	(41	)	$	150,293	$	(860	)

The Company conducts a regular assessment of its investment securities to determine whether securities are other-than-temporarily impaired considering, among other factors, the nature of the securities, credit ratings or financial condition of the issuer, the extent and duration of the unrealized loss, expected cash flows, market conditions and the Company’s ability to hold the securities through the anticipated recovery period.

The Company does not consider securities with unrealized losses at June 30, 2016 to be other-than-temporarily impaired. The Company does not intend to sell these investments and it is more likely than not that the Company will not be required to sell these investments before recovery of the amortized cost bases, which may be the maturity dates of the securities. The unrealized losses within each category have occurred as a result of changes in interest rates, market spreads and market conditions subsequent to purchase. Securities with continuous unrealized losses existing for more than twelve months were primarily corporate notes and mortgage-backed securities. Unrealized losses recognized on corporate notes and mortgage-backed securities are the result of increases in yields for similar types of securities.

The following table provides information as to the amount of gross gains and gross losses realized and proceeds received through the sale or call of investment securities:



	Three months ended June 30,						Six months ended June 30,
(Dollars in thousands)	2016			2015			2016			2015
Realized gains	$	1,487		$	14		$	4,037		$	567
Realized losses	(47		)	(38		)	(1,272		)	(67		)
Net realized gains (losses)	$	1,440		$	(24	)	$	2,765		$	500
Other than temporary impairment charges	—			—			—			—
Gains (losses) on investment securities, net	$	1,440		$	(24	)	$	2,765		$	500
Proceeds from sales and calls of available-for-sale securities	$	1,068,795		$	498,501		$	1,071,996		$	1,134,033
Proceeds from calls of held-to-maturity securities	183,738			—			281,981			—

The amortized cost and fair value of securities as of June 30, 2016, December 31, 2015 and June 30, 2015, by contractual maturity, are shown in the following table. Contractual maturities may differ from actual maturities as borrowers may have the right to call or repay obligations with or without call or prepayment penalties. Mortgage-backed securities are not included in the maturity categories in the following maturity summary as actual maturities may differ from contractual maturities because the underlying mortgages may be called or prepaid without penalties:



	June 30, 2016				December 31, 2015				June 30, 2015
(Dollars in thousands)	Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value
Available-for-sale securities
Due in one year or less	$	214,917	$	215,290	$	160,856	$	160,756	$	141,792	$	141,897
Due in one to five years	113,263		113,395		166,550		166,468		261,285		261,146
Due in five to ten years	28,111		30,870		228,652		225,699		291,451		285,192
Due after ten years	13,459		14,021		13,753		14,182		642,617		619,517
Mortgage-backed	203,012		207,508		1,110,101		1,092,597		819,637		800,101
Equity securities	51,426		56,579		51,380		56,686		48,740		54,208
Total available-for-sale securities	$	624,188	$	637,663	$	1,731,292	$	1,716,388	$	2,205,522	$	2,162,061
Held-to-maturity securities
Due in one year or less	$	—	$	—	$	—	$	—	$	—	$	—
Due in one to five years	27,505		27,738		19,208		19,156		—		—
Due in five to ten years	68,691		70,121		96,454		96,091		—		—
Due after ten years	896,015		912,320		769,164		762,864		—		—
Total held-to-maturity securities	$	992,211	$	1,010,179	$	884,826	$	878,111	$	—	$	—

Securities having a fair value of $1.4 billion at June 30, 2016 as well as securities having a carrying value of $1.2 billion and $1.1 billion at December 31, 2015 and June 30, 2015, respectively, were pledged as collateral for public deposits, trust deposits, Federal Home Loan Bank ("FHLB") advances, securities sold under repurchase agreements and derivatives. At June 30, 2016, there were no securities of a single issuer, other than U.S. Government-sponsored agency securities, which exceeded 10% of shareholders’ equity.