INVESTMENTS (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Summary of Held-To-Maturity and Available-For-Sale Investment Securities

The following is a summary of held-to-maturity and available-for-sale investment securities as of December 31, 2017:



	Held-to-maturity									Available-for-sale
(Dollars in thousands)	Amortized cost		Unrecognized gain		Unrecognized loss			Fair value		Amortized cost		Unrealized gain		Unrealized loss			Fair value
U.S. Treasuries	$	0	$	0	$	0		$	0	$	98	$	0	$	(1	)	$	97
Securities of U.S. government agencies and corporations	11,168		0		(76		)	11,092		15,695		220		0			15,915
Mortgage-backed securities - residential	162,093		2,042		(1,535		)	162,600		290,793		849		(2,599		)	289,043
Mortgage-backed securities - commercial	255,027		1,372		(3,000		)	253,399		150,356		164		(1,417		)	149,103
Collateralized mortgage obligations	143,545		354		(1,602		)	142,297		306,095		1,158		(1,861		)	305,392
Obligations of state and other political subdivisions	82,175		1,804		(266		)	83,713		124,269		2,162		(676		)	125,755
Asset-backed securities	0		0		0			0		377,655		1,628		(306		)	378,977
Other securities	0		0		0			0		83,266		2,147		(287		)	85,126
Total	$	654,008	$	5,572	$	(6,479	)	$	653,101	$	1,348,227	$	8,328	$	(7,147	)	$	1,349,408

The following is a summary of held-to-maturity and available-for-sale investment securities as of December 31, 2016:



	Held-to-maturity									Available-for-sale
(Dollars in thousands)	Amortized cost		Unrecognized gain		Unrecognized loss			Fair value		Amortized cost		Unrealized gain		Unrealized loss			Fair value
U.S. Treasuries	$	0	$	0	$	0		$	0	$	98	$	0	$	(1	)	$	97
Securities of U.S. government agencies and corporations	13,011		0		(110		)	12,901		7,056		0		(40		)	7,016
Mortgage-backed securities - residential	205,522		1,740		(1,166		)	206,096		184,960		1,175		(2,740		)	183,395
Mortgage-backed securities - commercial	278,728		3,254		(1,817		)	280,165		154,239		188		(826		)	153,601
Collateralized mortgage obligations	195,408		1,125		(1,476		)	195,057		232,701		634		(2,321		)	231,014
Obligations of state and other political subdivisions	70,585		117		(1,346		)	69,356		96,934		1,461		(1,514		)	96,881
Asset-backed securities	0		0		0			0		322,708		517		(2,013		)	321,212
Other securities	0		0		0			0		46,641		741		(728		)	46,654
Total	$	763,254	$	6,236	$	(5,915	)	$	763,575	$	1,045,337	$	4,716	$	(10,183	)	$	1,039,870

Summary of Investment Securities by Estimated Maturity

The following table provides a summary of investment securities by contractual maturity as of December 31, 2017, except for residential and commercial mortgage-backed securities, collateralized mortgage obligations and asset-backed securities, which are shown as single totals, due to the unpredictability of the timing in principal repayments:



	Held-to-maturity				Available-for-sale
(Dollars in thousands)	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	165	$	165	$	2,422	$	2,423
Due after one year through five years	4,492		4,494		37,064		37,149
Due after five years through ten years	2,500		2,723		82,404		84,168
Due after ten years	86,186		87,423		101,438		103,153
Mortgage-backed securities - residential	162,093		162,600		290,793		289,043
Mortgage-backed securities - commercial	255,027		253,399		150,356		149,103
Collateralized mortgage obligations	143,545		142,297		306,095		305,392
Asset-backed securities	0		0		377,655		378,977
Total	$	654,008	$	653,101	$	1,348,227	$	1,349,408

Age of Gross Unrealized Losses and Associated Fair Value by Investment Category

The following tables provide the fair value and gross unrealized losses on investment securities in an unrealized loss position, aggregated by investment category and the length of time the individual securities have been in a continuous loss position:



	December 31, 2017
	Less than 12 months					12 months or more					Total
(Dollars in thousands)	Fair value		Unrealized loss			Fair value		Unrealized loss			Fair value		Unrealized loss
U.S. Treasuries	$	97	$	(1	)	$	0	$	0		$	97	$	(1	)
Securities of U.S. government agencies and corporations	11,092		(76		)	0		0			11,092		(76		)
Mortgage-backed securities - residential	175,183		(1,109		)	108,782		(3,025		)	283,965		(4,134		)
Mortgage-backed securities - commercial	132,818		(1,713		)	72,139		(2,704		)	204,957		(4,417		)
Collateralized mortgage obligations	164,909		(1,138		)	101,436		(2,325		)	266,345		(3,463		)
Obligations of state and other political subdivisions	38,450		(507		)	21,639		(435		)	60,089		(942		)
Asset-backed securities	44,941		(200		)	24,396		(106		)	69,337		(306		)
Other securities	2,605		(1		)	7,124		(286		)	9,729		(287		)
Total	$	570,095	$	(4,745	)	$	335,516	$	(8,881	)	$	905,611	$	(13,626	)



	December 31, 2016
	Less than 12 months					12 months or more					Total
(Dollars in thousands)	Fair value		Unrealized loss			Fair value		Unrealized loss			Fair value		Unrealized loss
U.S. Treasuries	$	97	$	(1	)	$	0	$	0		$	97	$	(1	)
Securities of U.S. Government agencies and corporations	19,917		(150		)	0		0			19,917		(150		)
Mortgage-backed securities - residential	180,654		(3,621		)	9,890		(285		)	190,544		(3,906		)
Mortgage-backed securities - commercial	123,122		(1,200		)	65,007		(1,443		)	188,129		(2,643		)
Collateralized mortgage obligations	201,305		(2,882		)	42,314		(915		)	243,619		(3,797		)
Obligations of state and other political subdivisions	94,632		(2,710		)	12,023		(150		)	106,655		(2,860		)
Asset-backed securities	116,057		(764		)	92,629		(1,249		)	208,686		(2,013		)
Other securities	7,746		(237		)	21,357		(491		)	29,103		(728		)
Total	$	743,530	$	(11,565	)	$	243,220	$	(4,533	)	$	986,750	$	(16,098	)