Securities (Tables)

6 Months Ended

Jun. 30, 2016

Investments Debt And Equity Securities [Abstract]

Summary of Securities Held for Investment and Securities Available for Sale

The following table summarizes securities held for investment and securities available for sale:

	June 30, 2016		December 31, 2015
	(Dollars in thousands)
Held for investment, at cost (fair value: $8,372 and $8,850, respectively)	$	8,312	$	8,789
Available for sale, at fair value		410,926		544,160
Total	$	419,238	$	552,949

Summary of Amortized Cost and Estimated Fair Values of Securities Held for Investment

The following table summarizes the amortized cost and estimated fair values of securities held for investment:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
June 30, 2016	(Dollars in thousands)
Mortgage backed securities (1)	$	301	$	24	$	—	$	325
States and political subdivisions		7,511		36		—		7,547
Other securities		500		—		—		500
Total	$	8,312	$	60	$	—	$	8,372
December 31, 2015
Mortgage backed securities (1)	$	347	$	25	$	—	$	372
States and political subdivisions		7,942		36		—		7,978
Other securities		500		—		—		500
Total	$	8,789	$	61	$	—	$	8,850

Summary of Amortized Cost and Estimated Fair Values of Securities Available for Sale

The following table summarizes the amortized cost and estimated fair values of securities available for sale:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
June 30, 2016	(Dollars in thousands)
U.S. treasuries	$	204,183	$	2,343	$	—		$	206,526
U.S. federal agencies		125,083		618		(51	)		125,650
Mortgage backed securities (1)		20,966		403		(555	)		20,814
States and political subdivisions		46,460		1,644		(67	)		48,037
Other securities (2)		9,989		142		(232	)		9,899
Total	$	406,681	$	5,150	$	(905	)	$	410,926
December 31, 2015
U.S. treasuries	$	328,965	$	776	$	(45	)	$	329,696
U.S. federal agencies		131,522		527		(153	)		131,896
Mortgage backed securities (1)		21,973		425		(543	)		21,855
States and political subdivisions		49,521		1,447		(48	)		50,920
Other securities (2)		9,689		249		(145	)		9,793
Total	$	541,670	$	3,424	$	(934	)	$	544,160

(1) Primarily consists of FHLMC, FNMA, GNMA and mortgage backed securities through U.S. agencies.

(2) Primarily consists of equity securities.

Maturity of Securities

The maturities of securities held for investment and available for sale are summarized in the following table using contractual maturities. Actual maturities may differ from contractual maturities due to obligations that are called or prepaid. For purposes of the maturity table, mortgage-backed securities, which are not due at a single maturity date, have been presented at their contractual maturity.

	June 30, 2016				December 31, 2015
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(Dollars in thousands)
Held for Investment
Contractual maturity of debt securities:
Within one year	$	4,987	$	4,997	$	5,168	$	5,174
After one year but within five years		2,543		2,569		2,800		2,829
After five years but within ten years		760		784		795		319
After ten years		22		22		26		528
Total	$	8,312	$	8,372	$	8,789	$	8,850
Available for Sale
Contractual maturity of debt securities:
Within one year	$	182,254	$	182,608	$	272,820	$	272,779
After one year but within five years		140,232		143,197		178,617		180,145
After five years but within ten years		7,986		8,610		8,483		9,075
After ten years		69,695		70,104		75,522		75,853
Total debt securities		400,167		404,519		535,442		537,852
Equity securities		6,514		6,407		6,228		6,308
Total	$	406,681	$	410,926	$	541,670	$	544,160

Company's Book Value of Pledged Securities

The following table is a summary of the Company’s book value of securities that were pledged as collateral for public funds on deposit, repurchase agreements and for other purposes as required or permitted by law:

	June 30, 2016		December 31, 2015
	(Dollarsin thousands)
Book value of pledged securities	$	379,267	$	493,540