RETIREMENT PLANS: (Tables)

12 Months Ended

Dec. 31, 2017

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs

Net periodic benefit cost and other amounts recognized in other comprehensive income included the following components:

(Dollar amounts in thousands)	2017			2016			2015
Service cost - benefits earned	$	1,432		$	1,882		$	2,153
Interest cost on projected benefit obligation	3,621			3,729			3,516
Expected return on plan assets	(3,940		)	(3,429		)	(3,452		)
Net amortization and deferral	1,205			1,936			2,065
Net periodic pension cost	2,318			4,118			4,282
Net loss (gain) during the period	5,366			(6,150		)	(1,894		)
Amortization of prior service cost	(1		)	(1		)	(1		)
Amortization of unrecognized gain (loss)	(1,204		)	(1,935		)	(2,064		)
Total recognized in other comprehensive (income) loss	4,161			(8,086		)	(3,959		)
Total recognized net periodic pension cost and other comprehensive income	$	6,479		$	(3,968	)	$	323

Schedule of Defined Benefit Plans Disclosures

The information below sets forth the change in projected benefit obligation, reconciliation of plan assets, and the funded status of the Corporation's retirement program. Actuarial present value of benefits is based on service to date and present pay levels.

(Dollar amounts in thousands)	2017			2016
Change in benefit obligation:
Benefit obligation at January 1	$	93,233		$	90,855
Service cost	1,432			1,882
Interest cost	3,621			3,729
Actuarial (gain) loss	5,305			2,839
Benefits paid	(5,495		)	(6,072		)
Benefit obligation at December 31	98,096			93,233
Reconciliation of fair value of plan assets:
Fair value of plan assets at January 1	70,132			60,602
Actual return on plan assets	3,879			12,418
Employer contributions	2,933			3,184
Benefits paid	(5,495		)	(6,072		)
Fair value of plan assets at December 31	71,449			70,132
Funded status at December 31 (plan assets less benefit obligation)	$	(26,647	)	$	(23,101	)

Schedule of Assumptions Used

The accumulated benefit obligation for the defined benefit pension plan was $93.3 million and $88.5 million at year-end

2017 and 2016.

Principal assumptions used to determine pension benefit obligation at year end:	2017		2016
Discount rate	3.60	%	4.14	%
Rate of increase in compensation levels	3.00		3.00

Principal assumptions used to determine net periodic pension cost:	2017		2016
Discount rate	4.14	%	4.34	%
Rate of increase in compensation levels	3.00		3.00
Expected long-term rate of return on plan assets	6.00		6.00

Schedule of Allocation of Plan Assets

The Corporation's pension plan weighted-average asset allocation for the years 2017 and 2016 by asset category are as follows:

	Pension Plan Target Allocation	ESOP Target Allocation	Pension Percentage of Plan Assets at December 31,				ESOP Percentage of Plan Assets at December 31,
ASSET CATEGORY	2017	2017	2017		2016		2017		2016
Equity securities	25-75%	95-99%	72	%	68	%	98	%	99	%
Debt securities	0-50%	0-0%	25	%	29	%	—	%	—	%
Other	0-20%	0-5%	3	%	3	%	2	%	1	%
TOTAL			100	%	100	%	100	%	100	%

Schedule Of Fair Value Of Plan Assets

The fair value of the plan assets at December 31, 2017 and 2016, by asset category, is as follows:

			Fair Value Measurements at December 31, 2017 Using:
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Observable Inputs
(Dollar amounts in thousands)	Total		(Level 1)		(Level 2)		(Level 3)
Plan assets
Equity securities	$	48,152	$	48,152	$	—	$	—
Debt securities	10,717		—		10,717		—
Investment Funds	12,580		12,580		—		—
Total plan assets	$	71,449	$	60,732	$	10,717	$	—

			Fair Value Measurements at December 31, 2016 Using:
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Observable Inputs
(Dollar amounts in thousands)	Total		(Level 1)		(Level 2)		(Level 3)
Plan assets
Equity securities	$	51,170	$	51,170	$	—	$	—
Debt securities	11,566		—		11,566		—
Investment Funds	7,396		7,396		—		—
Total plan assets	$	70,132	$	58,566	$	11,566	$	—

Schedule of Expected Benefit Payments

Estimated Future Payments — The following benefit payments, which reflect expected future service, are expected:

PENSION BENEFITS
(Dollar amounts in thousands)
2018	$	5,837
2019	6,067
2020	6,166
2021	6,341
2022	6,474
2023-2027	35,078

Estimated Future Payments — The following benefit payments, which reflect expected future service, are expected:

(Dollar amounts in thousands)
2018	$	264
2019	266
2020	274
2021	265
2022	279
2023-2027	1,408

Schedule Of Weighted Average Assumptions

Weighted average assumptions at December 31:

	December 31,
	2017		2016
Discount rate	3.60	%	4.14	%
Initial weighted health care cost trend rate	5.00	%	5.00	%
Ultimate health care cost trend rate	5.00		5.00
Year that the rate is assumed to stabilize and remain unchanged	2018		2017

Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates

A one-percentage-point change in the assumed health care cost trend rates would have the following effects:

	1% Point		1% Point
(Dollar amounts in thousands)	Increase		Decrease
Effect on total of service and interest cost components	$	1	$	1
Effect on post-retirement benefit obligation	25		23

Pension Plan [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule of Amounts Recognized in Other Comprehensive Income (Loss)

Amounts recognized in accumulated other comprehensive income at December 31, 2017 and 2016 consist of:

(Dollar amounts in thousands)	2017		2016
Net loss (gain)	$	25,621	$	21,459
Prior service cost (credit)	3		4
	$	25,624	$	21,463

Postretirement Health Coverage [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule of Defined Benefit Plans Disclosures

Post-retirement health benefit expense included the following components:

	Years Ended December 31,
(Dollar amounts in thousands)	2017		2016			2015
Service cost	$	53	$	55		$	63
Interest cost	172		186			173
Net periodic benefit cost	225		241			236
Net loss (gain) during the period	83		(144		)	(200		)
Total recognized in other comprehensive income (loss)	83		(144		)	(200		)
Total recognized net periodic benefit cost and other comprehensive income	$	308	$	97		$	36

The Corporation uses a measurement date of December 31. Accrued post-retirement benefits as of December 31, 2017 and 2016 are as follows:

	December 31,
(Dollar amounts in thousands)	2017			2016
Change in benefit obligation:
Benefit obligation at January 1	$	4,276		$	4,383
Service cost	53			55
Interest cost	172			186
Plan participants' contributions	75			69
Actuarial (gain) loss	83			(144		)
Benefits paid	(298		)	(273		)
Benefit obligation at December 31	$	4,361		$	4,276
Funded status at December 31	$	4,361		$	4,276

Supplemental Employee Retirement Plans, Defined Benefit

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs

The amounts recognized in other comprehensive income in the current year are as follows:

(Dollar amounts in thousands)	2017		2016			2015
Net loss (gain) during the period	$	527	$	(511	)	$	(255	)
Amortization of prior service cost	—		—			—
Amortization of unrecognized gain (loss)	—		(57		)	(88		)
Total recognized in other comprehensive (income) loss	$	527	$	(568	)	$	(343	)

Schedule of Expected Benefit Payments

Estimated Future Payments — The following benefit payments, which reflect expected future service, are expected:

(Dollar amounts on thousands)
2018	$	—
2019	180
2020	352
2021	343
2022	334
2023-2027	1,593