Investment Securities
 3 Months Ended
Mar. 31, 2016
Investments, Debt and Equity Securities [Abstract]  
Investment Securities
Investment Securities Available-For-Sale
The following table shows investment securities available-for-sale.
(Dollars in thousands)
 
Amortized Cost
 
Gross Unrealized Gains
 
Gross Unrealized Losses
 
Fair Value
March 31, 2016
 
 

 
 

 
 

 
 

U.S. Treasury and Federal agencies securities
 
$
391,488

 
$
2,624

 
$
(42
)
 
$
394,070

U.S. States and political subdivisions securities
 
121,464

 
2,968

 
(123
)
 
124,309

Mortgage-backed securities — Federal agencies
 
237,234

 
4,153

 
(464
)
 
240,923

Corporate debt securities
 
34,183

 
393

 
(1
)
 
34,575

Foreign government and other securities
 
800

 
9

 
—

 
809

Total debt securities
 
785,169

 
10,147

 
(630
)
 
794,686

Marketable equity securities
 
1,893

 
5,670

 
(299
)
 
7,264

Total investment securities available-for-sale
 
$
787,062

 
$
15,817

 
$
(929
)
 
$
801,950

 
 
 
 
 
 
 
 
 
December 31, 2015
 
 

 
 

 
 

 
 

U.S. Treasury and Federal agencies securities
 
$
389,457

 
$
1,718

 
$
(1,506
)
 
$
389,669

U.S. States and political subdivisions securities
 
120,441

 
2,692

 
(143
)
 
122,990

Mortgage-backed securities — Federal agencies
 
234,400

 
3,430

 
(1,533
)
 
236,297

Corporate debt securities
 
34,241

 
199

 
(57
)
 
34,383

Foreign government and other securities
 
800

 
10

 
(1
)
 
809

Total debt securities
 
779,339

 
8,049

 
(3,240
)
 
784,148

Marketable equity securities
 
1,893

 
5,906

 
(220
)
 
7,579

Total investment securities available-for-sale
 
$
781,232

 
$
13,955

 
$
(3,460
)
 
$
791,727

 
At March 31, 2016 and December 31, 2015, the residential mortgage-backed securities held by the Company consisted primarily of GNMA, FNMA and FHLMC pass-through certificates which are guaranteed by those respective agencies of the United States government (Government Sponsored Enterprise, GSEs).
The following table shows the contractual maturities of investments in debt securities available-for-sale at March 31, 2016. Expected maturities will differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.
(Dollars in thousands)
 
Amortized Cost
 
Fair Value
Due in one year or less
 
$
144,949

 
$
145,669

Due after one year through five years
 
384,483

 
389,225

Due after five years through ten years
 
18,503

 
18,869

Due after ten years
 
—

 
—

Mortgage-backed securities
 
237,234

 
240,923

Total debt securities available-for-sale
 
$
785,169

 
$
794,686


The following table shows the gross realized gains and losses on sale of securities from the securities available-for-sale portfolio, including marketable equity securities. Realized gains and losses on the sales of all securities are computed using the specific identification cost basis.
 
 
Three Months Ended 
 March 31,
(Dollars in thousands)
 
2016
 
2015
Gross realized gains
 
$
10

 
$
—

Gross realized losses
 
—

 
—

Net realized gains (losses)
 
$
10

 
$
—

 
The following table summarizes gross unrealized losses and fair value by investment category and age.
 
 
Less than 12 Months
 
12 months or Longer
 
Total
(Dollars in thousands) 
 
Fair Value
 
Unrealized Losses
 
Fair Value
 
Unrealized Losses
 
Fair Value
 
Unrealized Losses
March 31, 2016
 
 

 
 

 
 

 
 

 
 

 
 

U.S. Treasury and Federal agencies securities
 
$
36,933

 
$
(42
)
 
$
—

 
$
—

 
$
36,933

 
$
(42
)
U.S. States and political subdivisions securities
 
12,169

 
(73
)
 
4,332

 
(50
)
 
16,501

 
(123
)
Mortgage-backed securities - Federal agencies
 
27,283

 
(111
)
 
19,467

 
(353
)
 
46,750

 
(464
)
Corporate debt securities
 
1,753

 
(1
)
 
—

 
—

 
1,753

 
(1
)
Foreign government and other securities
 
100

 
—

 
—

 
—

 
100

 
—

Total debt securities
 
78,238

 
(227
)
 
23,799

 
(403
)
 
102,037

 
(630
)
Marketable equity securities
 
347

 
(297
)
 
3

 
(2
)
 
350

 
(299
)
Total investment securities available-for-sale
 
$
78,585

 
$
(524
)
 
$
23,802

 
$
(405
)
 
$
102,387

 
$
(929
)
 
 
 
 
 
 
 
 
 
 
 
 
 
December 31, 2015
 
 

 
 

 
 

 
 

 
 

 
 

U.S. Treasury and Federal agencies securities
 
$
151,581

 
$
(928
)
 
$
43,372

 
$
(578
)
 
$
194,953

 
$
(1,506
)
U.S. States and political subdivisions securities
 
17,040

 
(79
)
 
3,795

 
(64
)
 
20,835

 
(143
)
Mortgage-backed securities - Federal agencies
 
78,731

 
(777
)
 
20,592

 
(756
)
 
99,323

 
(1,533
)
Corporate debt securities
 
9,340

 
(57
)
 
—

 
—

 
9,340

 
(57
)
Foreign government and other securities
 
99

 
(1
)
 
—

 
—

 
99

 
(1
)
Total debt securities
 
256,791

 
(1,842
)
 
67,759

 
(1,398
)
 
324,550

 
(3,240
)
Marketable equity securities
 
427

 
(218
)
 
3

 
(2
)
 
430

 
(220
)
Total investment securities available-for-sale
 
$
257,218

 
$
(2,060
)
 
$
67,762

 
$
(1,400
)
 
$
324,980

 
$
(3,460
)
 
The initial indication of other-than-temporary-impairment (OTTI) for both debt and equity securities is a decline in fair value below amortized cost. Quarterly, the impaired securities are analyzed on a qualitative and quantitative basis in determining OTTI. Declines in the fair value of available-for-sale debt securities below their cost that are deemed to be other-than-temporary are reflected in earnings as realized losses to the extent the impairment is related to credit losses. The amount of impairment related to other factors is recognized in other comprehensive income. In estimating OTTI impairment losses, the Company considers among other things, (i) the length of time and the extent to which fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer, and (iii) whether it is more likely than not that the Company will not have to sell any such securities before a recovery of cost.
There were no OTTI write-downs in 2016 or 2015.
At March 31, 2016, the Company does not have the intent to sell any of the available-for-sale securities in the table above and believes that it is more likely than not, that it will not have to sell any such securities before an anticipated recovery of cost. Primarily the unrealized losses on debt securities are due to increases in market rates over the yields available at the time the underlying securities were purchased. The fair value is expected to recover on all debt securities as they approach their maturity date or re-pricing date or if market yields for such investments decline. The Company does not believe any of the securities are impaired due to reasons of credit quality.
At March 31, 2016 and December 31, 2015, investment securities available-for-sale with carrying values of $284.11 million and $233.14 million, respectively, were pledged as collateral for security repurchase agreements and for other purposes.