(4) SECURITIES

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

	December 31,
	2016		2015
	(Dollars in thousands)
Held for investment, at cost (fair value: $4,403 and $8,850, respectively)	$	4,365	$	8,789
Available for sale, at fair value		465,468		544,160
Total	$	469,833	$	552,949

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
	(Dollars in thousands)
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
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

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
	(Dollars in thousands)
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
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.

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.

	December 31,
	2016				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	$	1,561	$	1,568	$	5,168	$	5,174
After one year but within five years		1,937		1,951		2,800		2,829
After five years but within ten years		707		723		795		319
After ten years		160		161		26		528
Total	$	4,365	$	4,403	$	8,789	$	8,850
Available for Sale
Contractual maturity of debt securities:
Within one year	$	66,542	$	66,662	$	272,820	$	272,779
After one year but within five years		320,150		319,839		178,617		180,145
After five years but within ten years		5,830		6,152		8,483		9,075
After ten years		66,199		66,246		75,522		75,853
Total debt securities		458,721		458,899		535,442		537,852
Other securities		6,594		6,569		6,228		6,308
Total	$	465,315	$	465,468	$	541,670	$	544,160

The following is a detail of proceeds from sales and realized securities gains and losses, on available for sale securities:

	Year Ended December 31,
	2016		2015		2014
	(Dollars in thousands)
Proceeds	$	481	$	10,850	$	4,855
Gross gains realized		227		9,394		1,641
Gross losses realized		286		125		—

Realized gains/losses are reported as securities transactions within the noninterest income section of the consolidated statement of comprehensive income.

During 2015 the realized gains were from the following transactions: Council Oak Investment Corporation, a wholly-owned subsidiary of BancFirst, recognized a pretax gain of approximately $1.7 million from the sale of one of its equity investments, Council Oak Partners, LLC, a wholly-owned subsidiary of the Company, recognized a pretax gain of approximately $5.2 million from the sale of one of its equity investments and the Company recorded a gain of $2.1 million related to the redemption of warrants associated with a past loan transaction.

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:

	Year Ended December 31,
	2016		2015
	(Dollars in thousands)
Book value of pledged securities	$	439,692	$	493,540

The following table summarizes securities with unrealized losses, segregated by the duration of the unrealized loss, at December 31, 2016 and 2015 respectively:

	Less than 12 Months				More than 12 Months				Total
	Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses
	(Dollars in thousands)
December 31, 2016
Held for Investment
Mortgage backed securities	$	7	$	—	$	9	$	—	$	16	$	—
States and political subdivisions		476		4		—		—		476		4
Total	$	483	$	4	$	9	$	—	$	492	$	4
Available for Sale
U.S. treasuries	$	103,705	$	920	$	—	$	—	$	103,705	$	920
U.S. federal agencies		71,511		357		9,619		48		81,130		405
Mortgage backed securities		3		—		14,834		567		14,837		567
States and political subdivisions		15,289		62		779		67		16,068		129
Other securities		—		—		589		150		589		150
Total	$	190,508	$	1,339	$	25,821	$	832	$	216,329	$	2,171
December 31, 2015
Held for Investment
Mortgage backed securities	$	21	$	—	$	—	$	—	$	21	$	—
States and political subdivisions		—		—		—		—		—		—
Total	$	21	$	—	$	—	$	—	$	21	$	—
Available for Sale
U.S. treasuries	$	139,762	$	45	$	—	$	—	$	139,762	$	45
U.S. federal agencies		46,948		118		5,969		35		52,917		153
Mortgage backed securities		59		—		14,844		543		14,903		543
States and political subdivisions		1,932		47		245		1		2,177		48
Other securities		304		142		105		3		409		145
Total	$	189,005	$	352	$	21,163	$	582	$	210,168	$	934

Declines in the fair value of held for investment and available-for-sale securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses. In estimating other-than-temporary impairment losses, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer and (iii) the intent and ability of the Company to retain its investment in the issuer for a period of time sufficient to allow for any anticipated recovery in fair value.

Management has the ability and intent to hold the securities classified as held for investment until they mature, at which time the Company will receive full value for the securities. Furthermore, as of December 31, 2016 and 2015, the Company also had the ability and intent to hold the securities classified as available for sale for a period of time sufficient for a recovery of cost. The unrealized losses are largely due to increases in market interest rates over the yields available at the time the underlying debt securities were purchased. The fair value is expected to recover as the securities approach their maturity date or repricing date or if market yields for such investments decline. Management does not believe any of the securities are impaired due to reasons of credit quality, and has no intent or requirement to sell before the recovery of the unrealized loss; therefore, the Company has not recognized any impairment in the Company’s consolidated statement of comprehensive income.