Securities (Tables)

3 Months Ended

Mar. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Amortized cost and fair value of investments classified as available-for-sale

	March 31, 2018
(Dollar amounts in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. Government agencies	$	13,797	$	13	$	(408	)	$	13,402
Mortgage Backed Securities - residential	204,967		1,335		(4,695		)	201,607
Collateralized mortgage obligations	357,971		81		(10,922		)	347,130
State and municipal obligations	226,771		2,948		(1,830		)	227,889
Collateralized debt obligations	8,496		7,034		—			15,530
TOTAL	$	812,002	$	11,411	$	(17,855	)	$	805,558

	December 31, 2017
(Dollar amounts in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. Government agencies	$	13,989	$	24	$	(318	)	$	13,695
Mortgage Backed Securities-residential	215,079		2,071		(1,812		)	215,338
Mortgage Backed Securities-commercial	1		—		—			1
Collateralized mortgage obligations	346,005		370		(6,705		)	339,670
State and municipal obligations	227,651		4,671		(700		)	231,622
Collateralized debt obligations	8,644		5,961		—			14,605
TOTAL	$	811,369	$	13,097	$	(9,535	)	$	814,931

Schedule of contractual maturities of debt securities

Contractual maturities of debt securities at March 31, 2018 were as follows. Securities not due at a single maturity or with no maturity date, primarily mortgage-backed and equity securities are shown separately.

	Available-for-Sale
	Amortized		Fair
(Dollar amounts in thousands)	Cost		Value
Due in one year or less	$	4,313	$	4,321
Due after one but within five years	30,613		31,131
Due after five but within ten years	77,372		78,672
Due after ten years	136,766		142,697
	249,064		256,821
Mortgage-backed securities and collateralized mortgage obligations	562,938		548,737
TOTAL	$	812,002	$	805,558

Schedule of gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities have been in continuous unrealized loss position

The following tables show the securities’ gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities have been in continuous unrealized loss position, at March 31, 2018 and December 31, 2017. 

	March 31, 2018
	Less Than 12 Months					More Than 12 Months					Total
			Unrealized					Unrealized					Unrealized
(Dollar amounts in thousands)	Fair Value		Losses			Fair Value		Losses			Fair Value		Losses
U.S. Government agencies	$	9,212	$	(191	)	$	3,419	$	(217	)	$	12,631	$	(408	)
Mortgage Backed Securities - Residential	$	114,928	$	(2,398	)	$	50,851	$	(2,297	)	$	165,779	$	(4,695	)
Collateralized mortgage obligations	200,046		(3,784		)	137,790		(7,138		)	337,836		(10,922		)
State and municipal obligations	65,612		(997		)	18,298		(833		)	83,910		(1,830		)
Total temporarily impaired securities	$	389,798	$	(7,370	)	$	210,358	$	(10,485	)	$	600,156	$	(17,855	)

	December 31, 2017
	Less Than 12 Months					More Than 12 Months					Total
			Unrealized					Unrealized					Unrealized
(Dollar amounts in thousands)	Fair Value		Losses			Fair Value		Losses			Fair Value		Losses
US Government entity mortgage-backed securities	$	9,321	$	(86	)	$	3,538	$	(232	)	$	12,859	$	(318	)
Mortgage Backed Securities - Residential	$	79,918	$	(425	)	$	53,815	$	(1,387	)	$	133,733	$	(1,812	)
Collateralized mortgage obligations	150,182		(1,418		)	146,750		(5,287		)	296,932		(6,705		)
State and municipal obligations	27,347		(183		)	18,660		(517		)	46,007		(700		)
Total temporarily impaired securities	$	266,768	$	(2,112	)	$	222,763	$	(7,423	)	$	489,531	$	(9,535	)

Rollforward of the credit losses recognized in earnings

The table below presents a rollforward of the credit losses recognized in earnings for the three month periods ended March 31, 2018 and 2017:

	Three Months Ended March 31,
(Dollar amounts in thousands)	2018		2017
Beginning balance	$	7,132	$	13,974
Increases to the amount related to the credit
Loss for which other-than-temporary was previously recognized	—		—
Reductions for increases in cash flows collected	—		—
Reductions for securities called during the period	—		(6,842		)
Ending balance	$	7,132	$	7,132