Securities (Tables)

9 Months Ended

Sep. 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:

	September 30, 2016		December 31, 2015
	(Dollars in thousands)
Held for investment, at cost (fair value: $4,601 and $8,850, respectively)	$	4,554	$	8,789
Available for sale, at fair value		469,184		544,160
Total	$	473,738	$	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
September 30, 2016	(Dollars in thousands)
Mortgage backed securities (1)	$	273	$	21	$	—		$	294
States and political subdivisions		3,781		28		(2	)		3,807
Other securities		500		—		—			500
Total	$	4,554	$	49	$	(2	)	$	4,601
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
September 30, 2016	(Dollars in thousands)
U.S. treasuries	$	204,350	$	1,773	$	—		$	206,123
U.S. federal agencies		192,271		494		(117	)		192,648
Mortgage backed securities (1)		20,467		379		(561	)		20,285
States and political subdivisions		42,412		1,354		(62	)		43,704
Other securities (2)		6,447		125		(148	)		6,424
Total	$	465,947	$	4,125	$	(888	)	$	469,184
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.

	September 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	$	1,637	$	1,646	$	5,168	$	5,174
After one year but within five years		2,162		2,179		2,800		2,829
After five years but within ten years		736		756		795		319
After ten years		19		20		26		528
Total	$	4,554	$	4,601	$	8,789	$	8,850
Available for Sale
Contractual maturity of debt securities:
Within one year	$	205,834	$	206,093	$	272,820	$	272,779
After one year but within five years		178,939		181,187		178,617		180,145
After five years but within ten years		6,608		7,088		8,483		9,075
After ten years		68,119		68,392		75,522		75,853
Total debt securities		459,500		462,760		535,442		537,852
Other securities		6,447		6,424		6,228		6,308
Total	$	465,947	$	469,184	$	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:

	September 30, 2016		December 31, 2015
	(Dollarsin thousands)
Book value of pledged securities	$	419,481	$	493,540