Securities (Tables)

9 Months Ended

Sep. 30, 2018

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, 2018		December 31, 2017
	(Dollars in thousands)
Held for investment, at cost (fair value: $1,447 and $2,303, respectively)	$	1,440	$	2,292
Available for sale, at fair value		475,640		467,703
Total	$	477,080	$	469,995

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, 2018	(Dollars in thousands)
Mortgage backed securities (1)	$	145	$	6	$	—		$	151
States and political subdivisions		795		1		—			796
Other securities		500		—		—			500
Total	$	1,440	$	7	$	—		$	1,447
December 31, 2017
Mortgage backed securities (1)	$	187	$	10	$	—		$	197
States and political subdivisions		1,605		3		(2	)		1,606
Other securities		500		—		—			500
Total	$	2,292	$	13	$	(2	)	$	2,303

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, 2018	(Dollars in thousands)
U.S. treasuries	$	403,213	$	—	$	(5,747	)	$	397,466
U.S. federal agencies		32,017		1		(178	)		31,840
Mortgage backed securities (1)		16,581		119		(566	)		16,134
States and political subdivisions		30,098		262		(160	)		30,200
Total	$	481,909	$	382	$	(6,651	)	$	475,640
December 31, 2017
U.S. treasuries	$	314,905	$	—	$	(2,103	)	$	312,802
U.S. federal agencies		89,098		82		(329	)		88,851
Mortgage backed securities (1)		18,358		204		(586	)		17,976
States and political subdivisions		41,937		554		(121	)		42,370
Equity securities (2)		6,527		71		(894	)		5,704
Total	$	470,825	$	911	$	(4,033	)	$	467,703

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

(2) Consisted of equity securities that are included in other assets in 2018.

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, 2018				December 31, 2017
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(Dollars in thousands)
Held for Investment
Contractual maturity of debt securities:
Within one year	$	495	$	496	$	1,036	$	1,034
After one year but within five years		370		371		623		627
After five years but within ten years		570		575		625		633
After ten years		5		5		8		9
Total	$	1,440	$	1,447	$	2,292	$	2,303
Available for Sale
Contractual maturity of debt securities:
Within one year	$	61,869	$	61,656	$	113,225	$	112,974
After one year but within five years		368,309		362,723		289,038		287,058
After five years but within ten years		5,047		5,225		6,222		6,500
After ten years		46,684		46,036		55,813		55,467
Total debt securities		481,909		475,640		464,298		461,999
Equity securities		—		—		6,527		5,704
Total	$	481,909	$	475,640	$	470,825	$	467,703

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, 2018		December 31, 2017
	(Dollarsin thousands)
Book value of pledged securities	$	428,057	$	440,069