Securities (Tables)

3 Months Ended

Mar. 31, 2017

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:

	March 31, 2017		December 31, 2016
	(Dollars in thousands)
Held for investment, at cost (fair value: $4,038 and $4,403, respectively)	$	4,003	$	4,365
Available for sale, at fair value		459,247		465,468
Total	$	463,250	$	469,833

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
March 31, 2017	(Dollars in thousands)
Mortgage backed securities (1)	$	233	$	15	$	—		$	248
States and political subdivisions		3,270		22		(2	)		3,290
Other securities		500		—		—			500
Total	$	4,003	$	37	$	(2	)	$	4,038
December 31, 2016
Mortgage backed securities (1)	$	252	$	17	$	—		$	269
States and political subdivisions		3,613		25		(4	)		3,634
Other securities		500		—		—			500
Total	$	4,365	$	42	$	(4	)	$	4,403

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
March 31, 2017	(Dollars in thousands)
U.S. treasuries	$	289,248	$	723	$	(538	)	$	289,433
U.S. federal agencies		105,166		307		(415	)		105,058
Mortgage backed securities (1)		19,369		271		(567	)		19,073
States and political subdivisions		38,856		853		(71	)		39,638
Other securities (2)		6,746		125		(826	)		6,045
Total	$	459,385	$	2,279	$	(2,417	)	$	459,247
December 31, 2016
U.S. treasuries	$	268,763	$	700	$	(920	)	$	268,543
U.S. federal agencies		129,674		373		(405	)		129,642
Mortgage backed securities (1)		19,949		290		(567	)		19,672
States and political subdivisions		40,335		836		(129	)		41,042
Other securities (2)		6,594		125		(150	)		6,569
Total	$	465,315	$	2,324	$	(2,171	)	$	465,468

(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.

	March 31, 2017				December 31, 2016
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(Dollars in thousands)
Held for Investment
Contractual maturity of debt securities:
Within one year	$	1,563	$	1,573	$	1,561	$	1,568
After one year but within five years		1,751		1,762		1,937		1,951
After five years but within ten years		673		687		707		723
After ten years		16		16		160		161
Total	$	4,003	$	4,038	$	4,365	$	4,403
Available for Sale
Contractual maturity of debt securities:
Within one year	$	75,206	$	75,378	$	66,542	$	66,662
After one year but within five years		308,182		308,229		320,150		319,839
After five years but within ten years		6,318		6,666		5,830		6,152
After ten years		62,933		62,929		66,199		66,246
Total debt securities		452,639		453,202		458,721		458,899
Equity securities		6,746		6,045		6,594		6,569
Total	$	459,385	$	459,247	$	465,315	$	465,468

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:

	March 31, 2017		December 31, 2016
	(Dollarsin thousands)
Book value of pledged securities	$	432,232	$	439,692